Studies of the Subtribe Tachyina ( Coleoptera : Carabidae : Bembidiini ) , Part I : A Revision of the Neotropical Genus Xystosomus Schaum

Erwin, Terry L. Studies of the Subtribe Tachyina (Coleoptera: Carabidae: Bembidiini), Part I: A Revision of the Neotropical Genus Xystosomus Schaum. Smithsonian Contributions to Zoology, number 140, 39 pages, 72 figures, 1973.— The neotropical genus Xystosomus Schaum is revised. Twenty-two species are described as new; ten of thirteen previously described species are retained as valid, with the other three names being reduced to junior synonyms; and the species originally described as Xystosomus insularis is transferred to the genus Tachymenis. A key to the species is given for adults and pertinent characteristics are illustrated. All taxa are described or redescribed and partially illustrated. Six infrageneric evolutionary lines are discussed and the characteristic body forms of four lines are illustrated in habitus. Distribution for each species is listed by locality, and a map shows the range of each species group. Evolutionary considerations, natural history, and behavior are discussed where data are available. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SI PRESS NUMBER 4770. SERIES COVER DESICN: The coral Montasirea cavernosa (Linnaeus). Library of Congress Cataloging in Publication Data Erwin, Terry L., 1940A revision of the neotropical genus Xystosomus Schaum. (His Studies of the subtribe Tachyina (Coleoptera: Carabidae: Bembidiini) pt. 1) (Smithsonian contributions to zoology, no. 140) 1. Xystosomus. I. Title. II. Series. III. Series: Smithsonian Institution. Smithsonian contributions to zoology, no. 140 QL1.S54 no. 140, pt. 1 [QL596.C2] 591'.08s [595.7'62] 72-12708 For lale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 Price 70 cents domestic postpaid or 50 cent! GPO Bookstore Studies of the Subtribe Tachyina (Coleoptera: Carabidae: Bembidiini), Part I: A Revision of the Neotropical Genus Xystosomus Schaum


ABSTRACT
Erwin, Terry L. Studies of the Subtribe Tachyina (Coleoptera: Carabidae: Bembidiini), Part I: A Revision of the Neotropical Genus Xystosomus Schaum.Smithsonian Contributions to Zoology, number 140, 39 pages, 72 figures, 1973.-Theneotropical genus Xystosomus Schaum is revised.Twenty-two species are described as new; ten of thirteen previously described species are retained as valid, with the other three names being reduced to junior synonyms; and the species originally described as Xystosomus insularis is transferred to the genus Tachymenis.A key to the species is given for adults and pertinent characteristics are illustrated.All taxa are described or redescribed and partially illustrated.Six infrageneric evolutionary lines are discussed and the characteristic body forms of four lines are illustrated in habitus.Distribution for each species is listed by locality, and a map shows the range of each species group.Evolutionary considerations, natural history, and behavior are discussed where data are available.
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year.SI PRESS NUMBER 4770.SERIES COVER DESICN: The coral Montasirea cavernosa (Linnaeus).

Introduction
This is the first paper to be issued in a long series that will review all groups of the subtribe Tachyina.My ultimate goal is a faunal analysis of the world Tachyina, hence the purpose of each part in the series is to present various data (taxonomy, natural history, behavior, distribution, etc.) for each genus or a generic group (if small numbers of species are included in each genus) in a way that can be used easily in the subsequent overall analysis.The present part deals with a moderatesized neotropical genus of mostly arboreal or subarboreal Tachyina.
The species of the genus Xystosomus have never been collectively reviewed.The literature consists of brief and mainly inconclusive species descriptions by Bates (11 species in five papers, 1871Bates (11 species in five papers, -1884) ) and Schaum (2 species in two papers, 1860Schaum (2 species in two papers, , 1863)).Other than in catalogs, I have seen no mention of the genus in the literature since the time that Bates and Schaum wrote, except for Darlington's (1939: 86) Xystosornus insularis, which is not a Xystosomus but a Tachymenis [Tachymenis insularis (Darlington), new combination] (Figure 2).
Terry L. Erwin, Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560.

Members of T. insularis have converged in body
form with members of Xystosomus so much that only a comprehensive study of all known species of Xystosomus and other primitive Tachyina has unveiled its true nature and its probable role in the evolution of the Tachyina; this will be discussed further in a forthcoming generic reclassification.
The immature stages of Xystosomus are unknown, but notes on habits and habitats of the adults were recorded by Bates (1871b) and by Nevermann on his excellent specimen labels.Also, my wife and I made observations of living beetles in the field and laboratory that supplemented observations made previously in Mexico by George Ball and me.This information is given under each pertinent species description and then summarized and analyzed under the section on natural history at the end of the paper.
Until now, the systematic concept of this genus was that of a heterogeneous assemblage of tachyinelike beetles with a great amount of diversity, but there was no clear evidence presented that they were related among themselves or to any other group (s) of the Bembidiini.With the benefit of a background study on all the rest of the world Tachyina, I conclude that the Xystosomus species form four general trends of evolutionary develop- ment (the gruti group trend, the elaphrinus group trend, the microtretus group trend, and the paminsularis-inflatus-laevis group trend).One of these trends, the latter, has been duplicated in members of at least one associated primitive genus, Tachymenis (wingless-globose body form).I have treated this latter complex as three species groups because I think they are morphologically convergent, all arising from different parts of the gruti group.I also conclude that the overall classification of Xystosomus and of some other genera of Tachyina is best handled in species groups rather than by erecting countless subgenera to reflect these evolutionary trends and other trends in the Tachyina.Lastly, I conclude that Xystosomus members form a link between Bembidion and its allies (Bembidiina) and Tachyina but that they are true Tachyina by virtue of numbers and kinds of apomorphic trends.The evidence for the above is presented below along with descriptions of new taxa and redescriptions of previously described taxa.
Phylogeny and zoogeography of Xystosomus species are discussed in only a general way here, but they will be elaborated upon in another part of the Tachyina study where all generic components can be discussed together.
ACKNOWLEDGMENTS.-I heartily thank the following persons for making this study possible: La Verne Erwin, my wife, for field work, measuring of specimens, and critically reading the manuscript; Prof. P. J. Darlington, Jr., for providing museum space, equipment, and discussion during a research fellowship at the Museum of Comparative Zoology (MCZ), and for the loan of specimens; Prof. C. H. Lindroth for providing working space, equipment, and discussion during a year's visit to Lund University in Sweden; Mme. A. Bons, Museum National d'Histoire Naturelle, Paris (MHNP), Prof. George E. Ball, University of Alberta, Edmonton, Canada (UASM), Mr. Peter Hammond, British Museum (Natural History), London (BMNH), Mr. Hugh B. Leech, California Academy of Sciences (CAS), Dr. F. Hieke, Zoological Museum of Humboldt University, Berlin (HUB), and Mr. J. Ne"gre, Versailles, France (JNeg), all for the loan of specimens in their charge or collection; to Mr. M. Druckenbrod for the line drawings of the pronota and maps; and to Mr. W. Brown of the Smithsonian's scanning electron microscope laboratory for the carefully made micrographs.
This study was supported in part by the American Philosophical Society (Penrose Fund #5795) through funds provided for type studies at the British Museum (Natural History) and the Museum National d'Histoire Naturelle, Paris, and in part by the environmental sciences program of the Smithsonian Institution through funds provided for field work, equipment, and support personnel.
METHODS.-This study is the result of the examination of more than 300 specimens of Xystosomus species and thousands of specimens of other Tachyina.Unfortunately, members of Xystosomus species are difficult to collect, and even though many major Neotropical collections were examined, very few (compared with other Tachyina groups) individuals were found.Hopefully, the informa-FICURE 2.-Male genitalia, left lateral aspect of Tachymenis insularis (Darlington) from Loma Vieja, Dominican Republic.tion here will stimulate collectors and natural historians to look in the proper habitats for these interesting beetles.
Methods of dissection, illustrations, and procedure (except as noted below) are the same as those used by me in the past (Erwin 1970(Erwin , 1972)).The short line accompanying the illustrations equals 1.0 mm unless otherwise noted.In the 1970 paper, I outlined my criteria for recognizing species, subspecies, and supraspecific taxa and they need not be repeated here.
I changed some parts of the format of species descriptions here to make them shorter and easier to use.For example, all data concerning aspects of natural history are given under that single heading rather than dividing them into separate statements, and a summary of all natural history data is given near the end of the paper.Also, variation is discussed separately from the description only where sufficient material was available from enough localities.I have seen all type-specimens mentioned.Finally, the species are numbered for easier reference between key, checklist, and descriptions.
Measurements used here are the width/length ratio (W/L) of the pronotum, total width, and total length.The width measurement of the pronotum is taken at the widest point and the length is taken along the midline, both of which are made with the pronotal plane level.W/L is given as x (mean ratio value for all specimens measured), together with the total range of ratio variation.Total length and width measurements are given only as a range of upper and lower limits on specimens seen.The length measurement is made as one measurement from the apex of the elytra to the anterior edge of the labrum unless the specimen is so bent that these points are out of focus, in which case the head, pronotum, and elytra are measured separately (Erwin 1970).The width is measured across the widest part of the elytra unless these are separated, and in this case each elytron is measured separately and the two resultant figures are added together.
The code for elytral chaetotaxy was published previously (Erwin 1972) and need not be duplicated here.The code is based on a study of all groups of known Tachyina, but it has an "openended" numbering system in case new setal posi-tions are discovered in poorly represented groups (e.g., Australian Region groups).
The abbreviations given in the acknowledgments indicate the museums or personal collections from which studied specimens were borrowed.The abbreviation used for the National Museum of Natural History (formerly United States National Museum) is USNM.Locality records are listed in the following order: Country, state and/or province, exact locality, and abbreviation of depository.
Checklist of Xystosomus species NUMBER 140 202), here designated, as Schaum did not designate either of his two species as the type (nor has any subsequent author); however, this is the firstmentioned species in Schaum's discussion.3,43,56): Broad and convex.Easily recognized from other Tachyina by the truncate anterior tibiae and absence of discal elytral setigerous pores.
Color: Body rufous to black, members of many species with metallic green luster or iridescence of pronotum and elytra; appendages usually testaceous or slightly infuscated, piceous in members of some species.
Head: Mentum with acute tooth on anterior margin, nonfoveate; antennae with pubescence on apical half of article 4 and on all of articles 5-11.
Mesothorax: Elytra with marginal explanation nonsetulose and nonserrate, recurrent groove moderately long and not quite parallel to side margin but closer to it than to suture, anterior apex of recurrent groove variously curved medially or not, elytral striae present or not (when present, punctulate or not or appearing as rows of serial punctures), intervals convex or flat, plica present, discal setigerous pores absent; coxae conjunct-confluent.
Abdomen: Last visible sternum of female with four setigerous pores in parallel row with posterior edge of that sternum; male with two setigerous pores.
Secondary sexual characteristics: Male with basal two anterior tarsal articles slightly dilated or broadly dilated and asymmetric, with modified setae beneath; male with two slender parameres, each with three to five setae, internal sac and apex of median lobe various; female with stylus of ovipositor bladelike with two stout spines laterally, one spine medially.

Key to Species Groups and Species
The members of the gruti group are characterized by similarities of the male genitalia, especially by the presence of a "brush sclerite" on the internal sac of the median lobe.The same kind of sclerite is also found well developed in all members of the genera Bembidion (except where secondarily reduced, for example in the vile group) and Asaphidion.Externally, the members of the gruti group are characterized by the following combination of characteristics: large eyes; large and strongly developed carinae posterolaterally on the pronotum; transverse pronotum wider than head across eyes; broadly explanate sides of the pronotum and elytra; presence of two pairs of lateral setigerous pores on the pronotum (except Xystosomus negrei); sulcate prosternal process; fully developed flight wings; and relatively large body size (some of the largest members of Tachyina).
Besides the combination above, many species of this group have members with iridescent or metallic green dorsal surfaces (the only Tachyina with metallic coloration) and deeply engraved, punctate elytral striae.
Presently representing this group are 16 species with a combined range (Figure 69) extending from southern Mexico to southern Brazil.DESCRIPTION.-Form(Figure 3): Large, broad, moderately convex (much less so than members of laevis group) with large head, narrow pronotum (compared with members of laevis group), and fully striate elytra.A variable species (see below) and easily distinguished from the similar X. ampliatus by the deeper lateral striae and the green metallic luster of the entire dorsal surface of the pronotum and elytra.
Color: Head and venter rufopiceous; pronotum and elytra dorsally with metallic green luster; appendages testaceous or partly infuscated.
Head: Broad between eyes; frontal furrows moderately impressed; eyes very large and prominent.
Secondary sexual characters: Male genitalia characteristic of the species group (Figure 23).Female genitalia characteristic of the species group (Figure 36).
VARIATION.-Thedepth of the elytral striae varies from deep to shallow.Northern South America (Peru) is a center for specimens with deep striae.To the north of this center, shallow or deep striae are found on Central American specimens, but only shallow striae are found on the Mexican specimens.To the south, either shallow or deep striae are found on the Brazilian specimens.Many more samples are needed to accurately assess this characteristic, but from preliminary data it appears that depth of striae is bimodal with shallower striae in the more temperate climates of the species' range.
Slight variation occurs in the shape of the apex of the male median lobe of the genitalia (Figures 23,24).This variation appears within population samples, however, and is not correlated with geographical area.
The great difference in size (see above) is also independent of geographical area.Both large and small individuals were collected in Costa Rica and Panama.All specimens from Brazil are large, but this may be sample bias, as there are only nine specimens.
NATURAL HISTORY.-InAugust, in Mexico, George Ball and I collected a male specimen that we saw running on the sun-lit bark of a fallen and partially burnt "buttress tree" after we disturbed some bracket fungi.On Barro Colorado Island, in December, my wife and I collected a female specimen in a pile of deep loose leaves under the crown of a recently fallen tree.The latter beetle was in the company of X. nigripalpis (see below for details).F. Nevermann's excellent collecting records pinned with each specimen give the following data (translated from German): "on leaf pile in sawmill, June," 2 specimens; "on leaves of Cedrela mexicana, May" (Meliaceae), 4 specimens; "on wilted foliage of Quararibae turbinata, October" (Bombacaceae), 10 specimens; "on dry wood of Pentaclethra filamentosa, March" (Leguminosae), 1 specimen; "on dry wood of Virola warbur gii, February" (Myristicaceae), 2 specimens; "under loose bark, November and June," 4 specimens; "wilted leaf of Acanthorhiza sp., June" (Phoenicaceae), 1 specimen; "at fermenting plant juice on freshly cut wood, August," 5 specimens; "at light, July," 1 specimen.I have observed a NUMBER 140 captive female from Barro Colorado Island in flight.
Further records indicate specimens were collected in September in Brazil, but no teneral specimens were seen to indicate at what season immatures might be discovered.
The altitudinal range of X. gruti is from near sea level on Barro Colorado Island to about 4,000 feet (1,219 m) on Volcan de Chiriquf, with most intermediate elevations represented on specimen labels.
In summary, this is a widespread and variable species occurring at low and medium elevations.In habits, it is probably arboreal, or at least subarboreal, and is capable of flight.Adults were collected in every month except January and April.It is probable that adults and immatures overlap.
BEHAVIOR.-Thespecimen from Barro Colorado Island was collected alive and was returned to Washington for further study (it is still alive at this writing).With only one individual, intraspecific reactions are not possible, but when this specimen and X. nigripalpis specimens are placed together in the same petri dish both demonstrate fierce aggressiveness.This reaction also occurs between members of X. nigripalpis and happens when two beetles come within "setal range" of each other (the elytral "Eo" setae on these beetles are very long).The result of contact is several quick lunges with the mandibles directed toward the other beetle.Many of my living specimens of X. nigripalpis are missing the apical articles of the antennae.
DISTRIBUTION (Figure 69).-The range of this species extends from Vera Cruz, Mexico, to Rio de Janeiro, Brazil.Throughout the range these beetles are distributed both at lower and middle elevations and in lowland tropical forests and cloud forests.
LOCALITY RECORDS (Figure 69).-I have seen at least 74 specimens (old cotypes in BMNH and MHNP not counted) from the following localities:   DESCRIPTION.-Form:As in X. gruti, but larger.Easily distinguished from X. gruti by the overall rufous color, less impressed lateral striae, and the broadly explanate sides of pronotum and elytra.
Head: As in X. gruti except frontal furrows less impressed, closer to eye margin; eyes very large and prominent.
Elytra: As in X. gruti except lateral striae less impressed than discal ones and explanations broader.
Microsculpture: As in X. gruti.Secondary sexual characters: Male unknown.Female genitalia characteristic of the species group.
NATURAL HISTORY.-Adults were collected in August and January.No teneral specimens were seen.Nevermann recorded a specimen in "fermenting plant juice on fresh cut wood, August" and a specimen "at night on dry wood of Sapotacca [PSapotaceae], January." LOCALITY RECORDS (Figure 69).-I have seen four specimens from the following localities: TYPE-SPECIMENS.-Theholotype male and allotype are in USNM.These and the paratypes were collected by my wife and me in 1971.Paratypes (21): CAS, 2; BMNH, 2; MCZ, 2; MHNP, 2; UASM, 2; USNM, 11.
DESCRIPTION.-Form:As in X. gruti except elytra slightly more convex.Easily distinguished by the piceous palpi, the nearly black integument of the dorsal surface, and the highly convex lateral intervals of the elytra.
Head: Frontal furrows moderately impressed; eyes large and prominent.
Elytra: Striae 1-8 of each elytron well impressed and punctulate to apical third, shallowly impressed and nonpunctulate in area of recurrent groove, lateral four striae more deeply impressed and more coarsely punctulate than discal striae, especially near base; lateral intervals convex to at least middle, flattened gradually to apical third, discal intervals less convex, at least in apical two-thirds; side margins broadly explanate; humeral projection moderately developed, well rounded; chaetotaxy as in X. gruti; plica small, evident externally.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia characteristic of the group (Figure 25).Female genitalia characteristic of the species group.
NATURAL HISTORY.-Thetype series was collected in and on deep litter at the crown of a fallen tree in the humid, tropical, semideciduous forest of Barro Colorado Island, Panama.The individuals were very active in sunlight (sparse as it was in this part of the forest) and shade, commonly running over undisturbed leaves and twigs.Most specimens were found in the deep leaf litter where the leaves were wilted but not decomposed.Our method of raking and reraking the leaves knocked most specimens to the soil, but close observation showed the beetles to be among the leaves off the soil.No specimens were teneral.All of these beetles were collected alive and taken to Washington for behavior studies and breeding purposes, the results of which will be published separately.(See also X. gruti, under Behavior.)I have observed captive specimens in flight.
LOCALITY RECORDS (Figure 69).-I have seen 23 specimens from the following locality: DESCRIPTION.-Form:Generally as in X. gruti except narrower, with more highly convex elytra, and with much smaller eyes.Color as in X. ampliatus but easily distinguished from that species by the narrower explanations of the pronotum and elytra.
Head: Narrow between eyes; frontal furrows deeply and broadly impressed; eyes moderately large and prominent; mouthparts as in Figures 4, 5.
Elytra: As in X. gruti except all striae evenly impressed and explanations narrower.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia (Figure 26) and female genitalia characteristic of the species group.
NATURAL HISTORY.-Unknown,except adults collected in August and September.No teneral specimens seen.

Xystosomus iris, new species
Head: Narrow between eyes; frontal furrows moderately impressed; eyes large and prominent.
Elytra: Striae 1-8 of each elytron well impressed and punctulate; punctures moderately large and separated by about twice their own diameter; recurrent groove doubled back into a deeply impressed elliptical loop; humeral projection well developed, sharply acute (oblique view); chaetotaxy as in X. gruti; plica short, evident externally.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia (Figure 27) and female genitalia characteristic of the species group.
NATURAL HISTORY.-Unknown,except adults collected in March (Bolivia) and October (Peru).No teneral specimens seen.
LOCALITY RECORDS (Figure 69).-I have seen six specimens from the following localities:  DESCRIPTION.-Form:As in X. strigosus, but easily distinguished from that species and all other species of the group by the longitudinal carinae of the pronotal disc.
Head: Narrow between eyes; frontal furrows moderately impressed with sharp carinae lateral to them near eye margin; eyes large and prominent.
Pronotum (Figure 11): Quadrate (W/L, x 1.46; range, 1.39-1.58;3 specimens), only slightly wider than head across eyes; disc with six longitudinal carinae, each separated from the other by deep sulci; hind angles about 90°, sides anterior to angles straight to about middle; side margins broadly explanate in basal half, narrowly explanate in apical half.
Elytra: Striae 1-8 of each elytron well impressed and punctate, entire though less impressed at apex; punctures large and well impressed, more so laterally, each contiguous with the next by a shallowly impressed stria, at least in basal half; recurrent groove doubled back into a hook, deeply impressed; chaetotaxy as in X. gruti; plica well developed externally, short.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia characteristic of the species group (Figure 28).Female genitalia characteristic of the species group.
NATURAL HISTORY.-Unknown,except that the specimen from Teffe was collected in the "1st quarter of 1879."No teneral specimens seen.
DESCRIPTION.-Form:As in X. strigosus, but easily distinguished from that species and all others in the group by the long carinae of the pronotum.
Color: Head and body dark piceous, almost black; pronotum and elytra shiny and slightly iridescent; appendages testaceous or slightly infuscated.
Head: Broad between eyes; frontal furrows short and deeply impressed; eyes medium-sized and slightly prominent.
Microsculpture: As in X. REMARKS.-Although the three known specimens do not possess the anterior pair of lateral setigerous pores, it is possible that this condition is variable.It is also possible that the longer carina of the pronotum effects the absence of a setigerous pore, making this the only species of the group without pores but with a longer carina.DESCRIPTION.-Form:As in X. gruti, except elytra slightly more convex.Easily distinguished from all other species of the group by the complete lack of elytral striae.
Head: Broad between eyes; frontal furrows moderately impressed; eyes large and prominent.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia characteristic of the species group (Figure 30).Female genitalia characteristic of the species group.
VARIATION.-Thelong series of specimens, all from the type, locality, is remarkably homogeneous, except in size and proportions of the pronotum.NATURAL HISTORY.-Unknown.
LOCALITY RECORDS (Figure 69).-I have seen 33 specimens from the following locality: SOUTH AMERICA: BOLIVIA: Cochabamba (MHNP, USNM) .DESCRIPTION.-Form:As in X. gruti, except elytra slightly more convex.Easily distinguished among the "smooth elytra-convex interval" group of species by the sinuate sides of the pronotum.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia (Figure 31) and female genitalia characteristic ol the species group.
LOCALITY RECORDS (Figure 69).-I have seen three specimens from the following locality: DESCRIPTION.-Form:As in X. gruti, except elytra more convex and shorter.The members of this species are not easily distinguished from other members of the "smooth elytra-convex interval" group of species on any one character state.Members of X. sublaevis are without the sinuate pronotal sides of X. anterocostis, without the coarsely punctate elytral rows of X. batesi, without the highly convex lateral intervals of X. sulcicostis, with some traces of striae or serial punctures, and therefore not like X. aetholius.
Head: Broad between eyes; frontal furrows short and sulcate; eyes large and prominent.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia (Figure 32) and female genitalia characteristic of the species group.
NATURAL HISTORY.-Thespecimen from Costa Rica was collected in April at 250 meters elevation.The original series of Bates was collected in Panama at 800 to 4,000 feet (244 to 1,220 m) elevation, but no date was recorded.No teneral specimens were seen.
LOCALITY RECORDS (Figure 69).-I have seen 16 specimens from the following localities: DESCRIPTION.-Form:As in X. gruti, except elytra much shorter and convex.Easily distinguished by the extended lateral intervals of the elytra; other similar species with smooth elytra have the convex intervals in basal half only.
Head: Broad between eyes; frontal furrows well impressed, sulcate posteriorly; eyes large and prominent.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia (Figure 33) and female genitalia characteristic of the species group.
12. Xystosomus apicisulcatus, new species DESCRIPTION.-Form:As in X. gruti.Easily distinguished from all species in the group by the sulcate apex of the sutural stria.
Head: Narrow between eyes; frontal furrows shallowly impressed; eyes very large and prominent.
Elytra: Each elytron with seven rows of partially striate serial punctulae; stria 8 deeply impressed, almost sulcate; recurrent groove very deeply sulcate and hooked at apex; apex of sutural and second row of punctulae deeply sulcate; side margins broadly explanate; humeral projection well developed, obtuse; chaetotaxy as in X. gruti; plica small, evident externally.
Secondary sexual characters: Male genitalia unknown.Female genitalia characteristic of the species group.
LOCALITY RECORDS (Figure 69).-I have seen only the unique type from Minas, Brazil.DESCRIPTION.-Form:As in X. gruti, except shorter.Easily distinguished by the absence of elytral microsculpture and the short frontal furrows.
Color: Head and body piceous; pronotum and head shiny; appendages tetaceous or partly infuscated.
Head: Narrow between eyes; frontal furrows deeply impressed, short, extended to mideye level; eyes large and prominent.
Elytra: Each elytron with seven rows of serial punctulae; stria 8 well impressed, coarsely punctate in basal half; punctulae of disc smaller and less impressed than those laterally, all rows effaced before apex; intervals flat, except interval 8 which is slightly convex; side margins broadly explanate; humeral tooth well developed, rounded; chaetotaxy as in X. gruti; plica small, evident externally.
Microsculpture: Head and pronotum as in X. gruti, except faintly impressed on pronotum; effaced from elytra.
Secondary sexual characters: Male genitalia unknown.Female genitalia characteristic of the species group.
LOCALITY RECORDS (Figure 69).-I have seen only the unique type from Petrdpolis, Brazil.DESCRIPTION.-Form:As in X. gruti, except elytra more convex.Easily distinguished from all species of the group by the complete lack of pronotal and elytral microsculpture.
Head: Narrow between eyes; frontal furrows linear and deeply impressed, extended to past mideye level; eyes large and prominent.
Elytra: Each elytron with eight rows of serial punctulae, laterally more coarsely punctulate and partially or totally striate (especially striae 7 and 8); discal intervals flat, lateral intervals slightly convex; otherwise as in X. gruti.
Secondaiy sexual characters: Male genitalia (Figure 34) and female genitalia characteristic of the species group.
NATURAL HISTORY.-Unknown,except adults collected in March and May.The specimen collected in May is slightly teneral.
LOCALITY RECORDS (Figure 69).-I have seen four specimens from the following locality: DESCRIPTION.-Form:As in X. gruti, except elytra more convex.Easily distinguished from all species of the group by the punctate elytra along with the coarse, meshed microsculpture which produces a matte-like finish on the elytra.
Color: Head and body piceous; forebody slightly darker than elytra especially toward apex of elytra; pronotum and elytra slightly iridescent; appendages testaceous.
Head: Narrow between eyes; frontal furrows deeply impressed, extended to just beyond mideye level; eyes large and prominent.
Elytra: Each elytron with eight rows of serial punctulae impressed at least in basal two-thirds; punctulae separated by their own diameter or more; extreme apex of row 2 sulcate; otherwise as in X. gruti.
Microsculpture: As in X. gruti except lines joined to form meshes on elytra (Figure 22g).
Secondary sexual characters: Male genitalia (Figure 35) and female genitalia characteristic of the species group.
NATURAL HISTORY.-Unknown,except adults were collected in February and the "second quarter" of the year.LOCALITY RECORDS (Figure 69).-I have seen seven specimens from the following localities: SOUTH AMERICA: BRAZIL: Minas Gerais Province: Rio Piracicaba (MHNP); Caraca (MHNP).Rio de Janeiro Province: Nova Friburgo (MHNP).DESCRIPTION.-Form:As in X. gruti, except elytra more convex.Easily distinguished by the large coarse punctures of the elytra along with the completely microsculptured dorsum.
Head: Broad between eyes; frontal furrows deeply impressed and linear, separated from eye by strongly developed carina; eyes medium-sized, moderately prominent.
Elytra: Each elytron with seven rows of serial punctures; laterally, punctures coarser and more deeply impressed; all rows effaced at apical sixth; row 8 absent; all intervals flat; side margins broadly explanate; humeral tooth well developed, blunt; chaetotaxy as in X. gruti; plica long, evident externally.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia unknown.Female genitalia characteristic of the species group.
LOCALITY RECORDS (Figure 69).-I have seen only the unique type from Caraca, Minas Gerais Province, Brazil.
eyes; narrow, almost square pronotum (narrower than head across eyes); nonsulcate prosternal process; and fully developed flight wings.
The characteristics of the internal sac of the male genitalia, including the presence of a "brush sclerite," correspond to those in the members of the gruti group.With the exception of the apex of the stylus, the characteristics of the female genitalia also correspond to those in the members of the gruti group.In the elaphrinus group, the apex is blunt, with the lateral spines exceeding it in length.
Color: Head and body piceous; pronotum and elytra with metallic green luster; appendages testaceous or piceous or bicolored.
Head: Broad between eyes; frontal furrows well impressed and separated from eye by a linear costa; eyes huge and hemispherical.
Elytra: Each elytron with eight rows of serial punctures, the lateral three or four rows also striate in part; punctulae and punctures larger and more coarsely impressed in rows 3-8 at base; all rows finer or effaced at apex; lateral intervals convex, discal intervals flat, intervals between coarse basal punctures uneven and partially convex; side margins broadly explanate; humeral projection well developed, obtuse; chaetotaxy as in X. gruti; plica short, evident externally.Microsculpture: As in X. gruti, except more finely impressed or nearly effaced in part; head shiny and without meshes.
Secondary sexual characters: Male genitalia characteristic of gruti group members in internal sac; median lobe larger, more twisted, and with bent apex (Figure 40).Female genitalia as in X. gruti, except stylus (Figure 42) blunt at apex, exceeded in length by lateral spines.
VARIATION.-Thespecimens I have seen can be divided into two groups on the basis of elytral punctation and leg color.One morph (all specimens south of the Amazon Basin or in the southern part of it) has each elytron with eight entire rows of numerous small serial punctulae with small, noncoarse punctures basally in rows 4-6.This morph has testaceous legs.The other morph (all specimens from French Guiana north) has each elytron with eight abbreviated rows of either small punctulae (rows 1 and 2) or large, coarse, well-impressed punctures (rows 3-8) with only rows 7 and 8 entire; rows 1-6 effaced in apical half.This morph has piceous or darkly infuscated legs.
Unfortunately, all "pale-legged morph" specimens are females.Further material, especially males, may clarify the situation and indicate whether the southern form is conspecific (or perhaps subspecific).The type-specimen is from an intermediate area, but it agrees in all respects to the northern "dark-legged morph." NATURAL HISTORY.-Adults were collected January to March, in May, July to September, and in November.One teneral specimen was collected in July.Nevermann recorded four specimens from "under loose bark, January, July, September, November"; one specimen "on tree fungus, February"; one specimen "off pieces of bark, May"; and one specimen "at light, May." DISTRIBUTION (Figure 70).-The range of this species extends from Costa Rica to the Amazon Basin in lowland tropical forests.
LOCALITY RECORDS (Figure 70).-I have seen 30 specimens from the following localities: DESCRIPTION.-Form:As in X. elaphrinus, although smaller and flatter; superficially resembling members of genus Notiophilus.Easily distinguished from the other two species of the group by the elytra, each of which has eight serial rows of small, even punctulae entire to apex.
Color: Head and body piceous; entire dorsal surface of head and body shiny with metallic green luster; appendages testaceous or partially infuscated.
Elytra: Each elytron with eight serial rows of small, even punctulae, each entire to apex; lateral rows more impressed than discal rows; otherwise as in X. elaphrinus.
Secondary sexual characters: Male genitalia unknown.Female genitalia characteristic of the species group.
NATURAL HISTORY.-Unknown,except adults collected in March.No teneral specimens seen.

Xystosomus spangleri, new species
Head: Very broad between eyes; frontal furrows shallowly impressed and separated from eyes by small rounded costae; eyes huge and hemispherical.
Elytra: Each elytron with eight serial rows of fine punctulae, all except row 8 effaced before apex; rows 6 and 7 almost effaced throughout; otherwise as in X. elaphrinus.
Microsculpture: As in X. elaphrinus, except almost effaced from elytra and more engraved on head.
Secondary sexual characters: Male genitalia (Figure 41) and female genitalia characteristic of the species group.
NATURAL HISTORY.-The two known specimens were collected in July in open country (either near a small pond or in grassland beneath cow patties), not in association with trees (P.J. Spangler and O. S. Flint, personal communications).
ETYMOLOGY.-Itake pleasure in naming this species after my colleague, Paul J. Spangler, who collected the types.
LOCALITY RECORDS (Figure 70).-I have seen two specimens from the following locality: CENTRAL AMERICA: PANAMA: Nine miles west of Los Algarrobos, near Rio San Pedro (USNM).
The microtretus group The members of the microtretus group are characterized by their small eyes, the lack of anterior pair of lateral setigerous pores on the pronotum, the presence of rudimentary laterobasal carinae on the pronotum, nonsulcate prosternum, fully developed flight wings, more broadly dilated articles of the male anterior tarsi, form of the recurrent groove, and peculiar male genitalia.When more specimens, and perhaps additional species, are known of this group, a subgeneric designation may be necessary.
The group presently consists of two species, one in Costa Rica and one in Brazil (Figure 70).-The holotype male, allotype, and one paratype male are in USNM.They were collected by Nevermann in 1925Nevermann in , 1934Nevermann in , and 1932, respectively. , respectively.DESCRIPTION.-Form(Figure 43): Medium-sized, broad, moderately convex (more so than X. gruti), with small flat eyes, narrow head, broad pronotum, and square humeri.Easily distinguished from the other species of the group (see below) by the form of the pronotum.
Head: Very broad between eyes; frontal furrows shallowly impressed posterior to clypeus, not prolonged onto frons beyond anterior margin of eye; eyes small, slightly prominent.
Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia (Figure 45) with internal sac quite different than in members of other species groups.Female genitalia (Figure 46) characteristic of the species group.
NATURAL HISTORY.-Adults were collected in January and February.No teneral specimens were seen.Nevermann recorded the finding of these beetles from "under loose bark," "on forest soil," and "sifted from soil." LOCALITY RECORDS (Figure 70).-I have seen three specimens from the following locality: DESCRIPTION.-Form:As in X. microtretus, but easily distinguished by the form of the pronotum, smaller eyes, and presence of eight rather than six rows of punctures on each elytron.
Head: Very broad between eyes; frontal furrows shallowly impressed and prolonged to posterior margin of eye; separated from supraorbital setigerous pores by narrow and sharp carinae; eyes small and nearly flat.
Elytra: Each elytron with eight rows of serial punctures, rows 2-7 effaced before apex; punctures large and coarse, separated by about their own diameter; side margins moderately explanate; humeral projection small, obtuse; chaetotaxy as in X. gruti; plica long, evident externally.Microsculpture: As in X. gruti.Secondary sexual characters: Male genitalia unknown.Female genitalia characteristic of the species group.
NATURAL HISTORY.Unknown, except the type was collected in "April-May."It is not teneral.
LOCALITY RECORDS (Figure 70).-I have seen only the unique type from Nova Friburgo, Brazil.

The parainsularis group
The members of the parainsularis group are characterized by similarities of the male genitalia, female genitalia, and pronotal structure.Externally, the forms appear to be diverse for two reasons: first, the body form of X. parainsularis is narrow while that of X. bisulcifrons is broad; second, the elytra of X. parainsularis are smooth while those of X. bisulcifrons are punctate.The result of these diversities is a superficially different appearance of the two species.Xystosomus parainsularis is similar in appearance to Tachymenis insularis (Darlington) while X. bisulcifrons is similar to a mix of gruti, inflatus, and microtretus group members.However, the male genitalia of the two species in the parainsularis group are very similar and would -J \ FIGURES 47,dorsal aspect: 47,Xystosomus parainsularis,male,"Colombia Oriental";48,X. bisulcifrons,male,Rio Parahyba,Brazil.fall between those of the gruti group and laevis group if placed in a morphocline.
There are two known species representing this group, one from Brazil and one from Colombia-Venezuela (Figure 71).DESCRIPTION.-Form:Elongate and convex with broad head and narrow pronotum.Easily distinguished from the other species of the group by the smooth elytra.
Color: Head and body rufopiceous; pronotum and head slightly darker than the elytra; appendages testaceous; antennae slightly infuscated apically.
Head: Very broad between eyes; frontal furrows moderately impressed; eyes large and prominent.
Secondary sexual characters: Male genitalia (Figure 49) and female genitalia (Figure 51) characteristic of the species group.
NATURAL HISTORY.-Unknown,except one adult collected in January.No teneral specimens seen.
pressed and separated by twice or more their own diameter; elytral-stria 8 present in apical third, deeply engraved, sulcate, nonpunctate; chaetotaxy as in X. in flatus except Eo5 and E06 with a sulcus between them; plica long, evident externally.Microsculpture: As in X. inflatus, except slightly coarser.
Secondary sexual characters: Male genitalia (Figure 50) characteristic of the species group.Female unknown.
Size: Holotype: length, 3.4 mm; width, 1.6 mm.NATURAL HISTORY.-Unknown,except the type was collected in September on the bank of a river.
LOCALITY RECORDS (Figure 71).-I have seen only the unique type from Parahyba River, Brazil.
The inflatus group With the exception of the bifoveate frons and the rather well-developed laterobasal carinae of the pronotum, the members of the inflatus group are very similar in appearance to the members of the laevis group.The male and female genitalia are of the same type, both groups are wingless, and both have partially fused elytra.These two groups, when better known, perhaps should be merged.I treat them as distinct groups here on the basis of the frons and pronotal structure.There are two known species of the inflatus group, both of which are known only from Brazil (Figure 72).(Schaum) FICURES 52,54,55,72 Tachys inflatus Schaum, 1859:202.[Lectotype, here selected, a female, in HUB.Type-locality: "Neufreiburg" (Nova Friburgo), Brazil.]

Xystosomus inflatus
DESCRIPTION.-Form:Short and broad, highly convex, and with a small depressed head.Easily distinguished from the other species of the group by the well-developed laterobasal carinae of the pronotum and the deep triangular fova formed medial to the carina.
Head: Narrow between eyes; frontal furrows short, arcuate, ended at anterior supraorbital setigerous pore; frons with two deeply impressed fovae each side of midline; eyes depressed, medium-sized, and prominent.
Secondary sexual characters: Male genitalia (Figure 54) and female genitalia (Figure 55) characteristic of the inflatus group.
NATURAL HISTORY.-Unknown,except adults collected in September, April, and May.No teneral specimens seen.
Microsculpture: As in X. inflatus.Secondary sexual characters: Male genitalia unknown.Female genitalia not investigated because of the poor condition of the specimen.
LOCALITY RECORDS (Figure 72).-I have seen only the unique type from Minas, Brazil.The laexris group Members of the leavis group are characterized by their broadly transverse pronota, greatly inflated and globular elytra, and small heads, together with a complete lack of impressed elytral striae, absence or partial absence of lateral pronotal setigerous pores (exception is X. impressifrons, with both sets present), and absence of flight wings.Besides these external characteristics, the internal sac and the apex of the median lobe of the male genitalia share great similarities (see illustrations).
The concordance of the above-mentioned characteristics indicates that the laevis group is a natural group of rather closely related forms that probably underwent speciation after the loss of powers of flight.This view is further supported by the group's very small range.The group is known to be composed of seven species, all of which are found in Brazil south of the Amazon Basin (Figure 72).
Microsculpture: As in X. laevis.Secondary sexual characters: Male unknown.Female genitalia characteristic of the species group.
NATURAL HISTORY.-Unknown,except one adult collected in July.No teneral specimens seen.
LOCALITY RECORDS (Figure 72).-I have seen ten specimens, all from the following locality: DESCRIPTION.-Form:As in X. laevis, except flatter and forebody narrower.Easily distinguished by the form of the pronotum with its basally convergent sides.
Elytra: Smooth; as in X. laevis except more prolonged apically.
Secondary sexual characters: Male genitalia (Figure 64) and female genitalia characteristic of the species group.
Size: Four specimens: length, 1.9-2.1 mm; width, 1.0-1.1 mm. group by the absence of lateral setigerous pores at the hind angles of the pronotum together with the obtuse hind angles of the pronotum.
Elytra: Smooth; seta Eo4 in position d rather than c; plica small, evident externally.
Microsculpture: As in Figure 22d,e.Secondary sexual characters: Male unknown.Female genitalia characteristic of the species group.

Natural History
The available habitat data indicate that some species of Xystosomus are arboreal, or at least subarboreal (gruti group members, 7 of 32); some are possibly associated with water (one member of gruti group and one member of elaphrinus group, 2 of 32); and one (a member of the microtretus group) has been found in the soil or under bark.No data are available for members of the laevis and parainsularis groups.
Habits and habitats are known best for members of the gruti group.Five species have been recorded in association with wood (twigs, limbs, or bark) or with leaves.My wife and I have observed members of both X. gruti and X. nigripalpis running among wilted leaves and on twiglets of a fallen tree where there was little or no direct sunlight.Ball and I found one individual of X. gruti running on a fallen "buttress tree" after we disturbed a bracket fungus.This log was in the direct sunlight.My living colonies of these two species always are active in daylight, never at night; thus, it is probable that No conclusions can be made in regard to periods of activity of the elaphrinus group, as only one specimen of X. elaphrinus has been recorded at light.Two specimens of X. spangleri were "probably" associated with pools of water in pastures (or possibly beneath cow manure in the pastures), according to P. J. Spangler and O. S. Flint (personal communications).The members of this group look very much like Elaphrus spp., and it is not difficult to imagine them in the same ecological role in the tropics where no species of Elaphrus occur.However, Nevermann recorded X. elaphrinus in the same habitats as members of the gruti group.Much more field work must be done to discover the true nature of the elaphrinus group.
Members of the microtretus group (X.microtretus) have been sifted from forest soil.The group's members are characterized by small eyes, and the males have broadly dilated and asymmetrical anterior tarsal articles.The collecting records and these character states lead me to suggest that the microtretus group is subepigean.Species of this group probably occur in heavily shaded areas in deep litter and do not come to light.The leaf-and twigrunning members of the gruti group do not have sjnall eyes, nor do they have the bulky articles of the male tarsi found in members of the microtretus group.The large eyes of the gruti group might be required to see diurnal predators (birds, lizards, and spiders and other insects) and, in fact, are common to many diurnal carabid beetles (Cicindelini, Elaphrini, Notiophilini, Anthiini, Graphopterini, and all diurnal bark-, leaf-, and twig-running groups I know).The bulky asymmetrical tarsal articles are very common in terrestrial forms, but not in arboreal groups.Larger arboreal carabids either have symmetrical padded tarsi (leaf runners) or long, narrow articles (bark-twig runners); many have pectinate claws, although members of Xystosomus do not.
The data available for determining annual periods of activity are very scanty.Most specimens used for this study are old, and most 18th-and 19th-century carabid collectors did not make exact date labels.However, enough data are available for me to make some general comments.Adults are present in the fauna throughout the year.Teneral adult records indicate March and September as possible months of larval or pupal presence, but this possibility is weakly supported and is noted here as simply a "place to start" in immature studies.The known data are given for each species to stimulate interest in obtaining immature records.I have observed only two species of this genus alive; hence, only tentative comments on behavior can be made now.Extreme aggressiveness occurs in both X. gruti and X. nigripalpis.When two individuals come within "setal range" (the elytral setae-Eo series-are very long), both will attack each other head to head, apparently chewing off antennae (many specimens in my living colonies exhibit this loss).These traits are observed under caged conditions, of course, but the same aggressive behavior occurs among other diurnal carabids (e.g., Cicindela spp.) in the field.
Additional aspects of behavior and natural history will be published separately as studies progress.

Evolutionary Considerations
In addition to the general hypothetical comments below, another paper will discuss in detail an analysis of the phylogeny of Tachyina based on Hennig's (1966) principles.The details and evidence of the phylogeny of Xystosomus will be presented there in relation to other tachyine groups.
Six apparent lines of evolution occur in the external and genitalic forms of extant Xystosomus species.
The gruti group is composed of Bembidion-like beetles with arboreal habits.These species are the most generalized of the genus and have characteristics found in Bembidion (metallic color, brushsclerite of the male genitalia, overall habitus, etc.) but not elsewhere in the Tachyina.With the Tachyina, the group shares other characteristics (complete sutural stria, recurrent groove on the elytral apex, biperforate procoxal cavities, etc.) not found in Bembidion or its close allies.Because of these distributions of characteristics and others (e.g., truncate anterior tibial apex), the group should be regarded as primitive Tachyina which diverged from the main line of Tachyina evolution shortly after Bembidiina and Tachyina diverged.Since that time, five lines have emerged from the generalized gruti group stock to take separate, but similar or slightly different, evolutionary pathways.
The elaphrinus group is closely related to the gruti group, differing only in minor details of genitalic form, width of pronotum, and eye size.All species of the group are fully winged, and the total geographical range is nearly as large as that of the gruti group.It is probable that this group is a rather recent off-shoot of the gruti group as compared with the following groups.
The laevis group apparently has been separate from the gruti group for a long time.Flight has been lost by the laevis group, and it is probable that extant species have evolved from winglessflightless ancestors.With no fossil records it is impossible to determine the age of the group, but reduction of sclerites, muscles, total loss of wing membranes, and partial fusion of elytra must have required a great deal of time in lowland tropical situations (see also Darlington, 1971:246).The restricted total range of the laevis group (Figure 72) is indicative of its immobility or, alternatively, of its restriction or withdrawal and of its specialization.No habitat data are available, but similar habitus forms such as Tachymenis insularis, Tachymenis spp., Elaphropus halipoides, Elaphropus caraboides, and Tachys trunci are arboreal, usually are found on leaves, in "Spanish moss" (Tillanzia sp.), or beneath bark, and it is probable that members of the laevis group are also arboreal, or, at least, subarboreal, but not necessarily "runners" as described above.
The infiatus and parainsularis groups fall between the two above lineages in body form as "missing link" groups, but this position is apparent rather than real.Members of both these groups are wingless and flightless, having some or all of the muscle and sclerite reduction found in the laevis group.The infiatus group (X.infiatus) has strongly developed laterobasal carinae on the pronotum similar in structure to those of members of the gruti group or weakly developed carinae (X.convexus) that are still larger than any of the laevis group.However, the male genitalia are quite similar to those of the laevis group.In this case, the complex structure of the male genitalia, especially the internal sac of the median lobe, must be weighted more than the character states of carinae.The latter form a morphocline and either are a result of convergence with members of the gruti group or, more likely, an indication that members of the infiatus group are retaining a gruti group characteristic while the laevis group has lost it.Both the laevis and infiatus groups probably were derived from the gruti group long ago, subsequently diverged from each other, and since have become independently wingless endemics with a small amount of "postflight" speciation.
The parainsularis group has not undergone postflight reduction of flight components to the extent that members of the infiatus group or laevis group have, and in this respect it probably is convergent to these groups.Its much broader range (Colombia to Brazil), rather than restriction to a small area in southern Brazil, supports this conclusion.Externally, the group's two members are diverse in habitus, but the male genitalia are characteristically of the same type and much closer to the gruti group type than to the laevis group type.This, together with the well-developed pronotal carinae of both species and the general body form of X. bisulcifrons, indicate to me that this group is another independent off-shoot of the gruti group.The remarkable convergence in body form between X. parainsularis and Tachymenis insularis of the West Indies is of special interest.
The microtretus group is less well known than the above-named groups due to the paucity of available material; however, some hypotheses can be made.Morphologically, it appears to me that two possibilities exist: either the group is an off-shoot of the gruti group that has become subsequently adapted to the subepigean environment, or it is an early derivative of the proto-Xystosomus stock, retaining Bembidion characteristics different from those retained by the gruti group.The male copulatory organ of X. microtretus does not help clarify the matter at all.Its general structure is similar to the male copulatory organ of certain species groups of Paratachys, a very remotely related group of derivative Tachyina.These similarities must be considered convergence.Because of the amount and nature of differences between this group and other Xystosomns groups, it is possible that this group should be regarded as a distinct genus or subgenus forming a sister group to Xystosomus.However, because of the small amount of material available for study I do not think it is justifiable to erect a new name at this time.

FIGURES
FIGURES 17, 69 TYPE-LOCALITY.-Minas,Brazil.TYPE-SPECIMEN.-The unique holotype female is in MHNP.It was collected by Squires.DESCRIPTION.-Form:As in X. gruti.Easily distinguished from all species in the group by the sulcate apex of the sutural stria.Color: Head and body piceous; pronotum and elytra slightly iridescent; appendages testaceous.
FIGURES 38, 70 TYPE-LOCALITY.-Jatahy,Goyaz Province, Brazil.TYPE-SPECIMENS.-Theholotype female is in MHNP.Three paratypes: MHNP, 2; USNM, 1.All four were collected by Donckier in 1903.DESCRIPTION.-Form:As in X. elaphrinus, although smaller and flatter; superficially resembling members of genus Notiophilus.Easily distinguished from the other two species of the group by the elytra, each of which has eight serial rows of small, even punctulae entire to apex.Color: Head and body piceous; entire dorsal surface of head and body shiny with metallic green luster; appendages testaceous or partially infuscated.Head: Very broad between eyes; frontal furrows moderately impressed and separated from eye by small rounded costae; eyes huge and hemispherical.

FICURES
.-Nine miles west of Los Algarrobos (near Rio San Pedro), Panama.TYPE-SPECIMENS.-Theholotype male and allotype are in USNM.Both were collected by P. J. Spangler in July 1967.DESCRIPTION.-Form:As in X. elaphrinus, although flatter.Easily distinguished from the other two species of the group by the very shallowly im-pressed rows 7 and 8 of elytral punctulae.

FIGURE 72
FIGURE 72.-Approximate range of the inflatus and laevis groups.
FIGURE 70 Approximate ranges of the elaphrinus group (crosshatched area) and the microtretus group (solid areas).they