Review of Loxopus Townes (Hymenoptera, Ichneumonidae, Cryptinae), with descriptions of six new species

The taxonomic limits of Loxopus Townes are reviewed. The genus is characterized by the lateral margin of the clypeus projecting as subtriangular lobe; lateral lobes of fourth tarsomeres distinctly longer than mesal lobes; fore wing vein 3r-m absent; hind wing vein 2-1A absent or vestigial; and first metasomal tergite with a basolateral tooth. It occurs from Mexico to southern Brazil. Nine species are recognized, of which six are described as new: L. dodecius Santos et Aguiar, L. duckei Santos et Aguiar, L. exius Santos et Aguiar, L. ichilus Santos et Aguiar, L. tenuis Santos et Aguiar, and L. venezuelanus Santos et Aguiar. The type species, L. australis Townes, and L. multicolor Kasparyan et Ruíz-Cancino are redescribed, and a diagnosis is provided for L. unicolor Kasparyan et Ruíz-Cancino, not examined. All studied species are illustrated and distribution records are mapped. An identification key for the species of Loxopus is presented. http://zoobank.org/urn:lsid:zoobank.org:pub:5B73E8B4-1288-4FD9-AABD-845B5085FFE3


Introduction
Loxopus Townes was described in 1970 as a new Neotropical genus characterized mainly by the hind wing vein 2-1A absent or vestigial, apicolateral margin of clypeus projecting as a subtriangular lobe and lateral lobes of fourth tarsomeres at least 1.5 × as long as mesal lobes (Townes 1970). Only one species was described, L. australis, although Townes stated that he had examined six species. Kasparyan and Ruíz-Cancino (2005) described two additional species from Mexico, L. unicolor and Diagnosis Apical margin of clypeus laterally projecting as delicate to distinct triangular lobes (Figure 2A,B); mesosoma matt and densely covered with short pilosity; epomia short and delicate; lateral lobe of t4 much longer (at least 1.5×) than mesal lobe ( Figure 2D); posterior transverse carina of propodeum forming weak but distinct sublateral crests; fore wing cell 1 + 2Rs (areolet) small, open, vein 3r-m absent; hind wing vein M + Cu subapically strongly arched; vein 2-1A almost always absent or vestigial ( Figure 2C).
Thorax. Generally matt and densely covered with dense and short pilosity. Dorsal margin of pronotum regular, not swollen; epomia short and delicate, divergent from pronotal collar. Mesoscutum subcircular, finely punctate; notaulus weakly impressed, in dorsal view distinct approximately on anterior 0.4 of mesoscutum; mesoscutum surface over notaulus with weak transverse wrinkles. Epicnemial carina restricted to ventral 0.5-0.8 of mesopleuron; sternaulus complete, weakly sinuous, striate, moderately impressed, weaker at posterior 0.35; median portion of posterior transverse carina of the mesothoracic venter short, straight. Hind margin of metanotum with small tooth-like projection; transverse furrow at base of propodeum narrow and moderately deep, with faint to distinct transverse striae. Pleural carina absent, or sometimes vestigial, often apparently present because of sculpture patterns of propodeum and metapleuron; juxtacoxal carina absent. Foretibia of female regular, not swollen; all t4 bilobed, lateral lobe at least 1.5 × as long as mesal lobe ( Figure 2D).

Males
Generally similar to the respective females. Morphological secondary sexual differences are usually more or less uniform within Cryptini, as noted by Santos and Aguiar (2013), and apply to the males of Loxopus as follows. General body size usually smaller than respective females. Antenna with 24-26 flagellomeres (body-size related), each flagellomere usually shorter and wider than in females; white band of flagellum starting more apically and usually covering more articles than in females of the same species. Transverse furrow usually slightly longer than in female. Propodeum smaller, less strongly convex, sublateral crests usually less distinct than in female ( Figure 7F). Spiracle of propodeum usually circular or weakly elongate, SWL 1.00-1.50. Brownish spot on fore wing absent. First metasomal segment more slender, with T1LW around 2.6 (2.10-3.11), and less widened apically, with T1WW around 1.6 (1.41-1.79). T2-7 much more slender than in females.

Comments
All species of Loxopus are very similar in sculpturing, biometric ratios and colour pattern, usually being recognized by slight but distinctive features, particularly in the colour pattern. All of them agree well with the original definition of the genus. The unequal lobes of t4, hind wing vein 2-1A indistinct and the triangular projections at the margin of the clypeus suffice to distinguish Loxopus from all other Neotropical genera of Cryptinae. The projections on the clypeal margin, though, are usually quite inconspicuous and need to be examined under high magnification and proper lighting. The taxa described herein should run properly in the key provided by Townes (1970) for the world genera of Goryphina, except for the specimens of L. duckei sp. nov. that have a developed vein 2-1A ('brachiella' of Townes). In the ninth couplet of the key, the character 'brachiella absent, or present and short, not reaching more than half the distance to wing margin' could lead the user to the Afrotropical genus Bozakites Seyrig, though that is not the only character of the couplet. The available description and illustrations of Bozakites, however, should suffice to distinguish any species of Loxopus from it.

Sampling and biodiversity
The vast majority of the specimens examined in this work were collected with Moericke (yellow pan) traps, mostly as part of an extensive program of field trips that also used several Malaise traps, in the same sites and during the same period. This is in agreement with the findings by Aguiar and Santos (2010), suggesting that Moericke traps outperform Malaise traps in collecting many cryptine taxa, including Loxopus. The strong sex bias towards females observed herein is also in agreement with the results yielded by Moericke traps in Aguiar and Santos (2010). The collection of 41 specimens of L. australis in two days in Anchieta, Brazil, with a total effort of 720 trap-days (unpublished data) is particularly remarkable. This sampling success (one specimen for every 17.6 trap-days) contrasts with the few specimens reported in the literature so far, and may support the idea that Loxopus is a rather abundant group.

Biology
Unknown.
Colour. Head black and whitish; mesosoma, legs and metasoma ferruginous. Head: black; scape dorsally dark brown (105,079,055), ventrally ferruginous; pedicel with elongate white spot, remainder of pedicel and first flagellomeres brown, getting darker toward apex, apical segments black; dorsal portion of f6-9 white; supraclypeal area, clypeus, mouth parts, base of mandible and malar space, lower 0.5 of gena and orbital band on supra-antennal area and vertex, whitish (230,215,188); apex of mandible blackish. Mesosoma: ferruginous (137,116,079); propleuron, collar, short dash on dorsal margin of pronotum, tegula and subalar ridge, dorsal division of metapleuron, usually apical 0.4 of metapleuron, transverse marks over propodeal crests, whitish; postscutellum lighter than body. Legs: ferruginous, generally slightly darker towards apex; fore and mid coxae and trochanter white, mid trochanter with fore and hind black spots on base and white spot on apex; mid trochantellus and hind trochanter and trochantellus marked whitish and dark brown; apical tarsi dark brown; hind coxa with fore and hind portions white, lateral part with broad stripe which is ferruginous on base and darker towards apex and hind part. Wings hyaline, fore wing with dark spot covering apical part of cells 2 + 3M and 1 + 2R1. Metasoma: ferruginous; apical 0.2 of T1, buff lateral areas on T2-4 (larger in T3) and median dorsal areas on T7-8 white; T2-3 sometimes fuscous (221,157,113) apically; ovipositor reddish orange (110,061,031); sheaths dark brown.

Male
Similar to female, except for the following: fore wing 4.40-5.10 mm; mandible more strongly triangular; antenna with 24-25 flagellomeres; apical transverse carina of propodeum placed more apically than in female, not forming sublateral crest; flagellum without white band, apical white stripe at T1 weak or absent, and T7-8 not white dorsally. SWL 1.00-1.33; T1LW 2.78-3.11; T1WW 1.41-1.57. Variation in pattern of white marks apply as in females.

Variation
Fore wing 3.92-5.32 mm long. Antenna with 23-25 flagellomeres; pedicel sometimes without dorsal white spot; f10-11 and apical half of f5 and f12 sometimes white; first flagellomere ranging from light to dark brown; pronotum posteriorly sometimes with sparse blackish areas; scutellum whitish on some specimens; propodeum sometimes with sparse blackish marks. Tones of ferruginous of the body vary from very light, yellowish, to dark, brownish; this might be at least partially related to specimen conservation and age. Mesopleuron sometimes with pale to distinct whitish mark; whitish mark on metapleuron varying from white and distinct to almost indistinct, sometimes represented by a buff, slightly paler area ( Figure 7D). Postscutellum sometimes completely white. Specimens from southern Brazil usually with more evident whitish spots on mesopleuron and metapleuron. Darker specimens with more extensive dark spots on hind coxa and sometimes with sparse blackish spots on mesoscutum and T2.

Comments
Readily recognizable by having all tergites of the metasoma mostly ferruginous, with lateral whitish marks, and sometimes with sparse blackish areas. Further isolated from all other species of the genus by the following combination of characters: supraclypeal area whitish, without blackish spots; lower 0.5 of gena whitish; postscutellum whitish; fourth tarsomeres lateral lobe 2.8 × as long as mesal lobe; dorsal valve of ovipositor without distinct nodus; ventral valve with six distinct teeth. Loxopus australis seems to be by far the commonest species of the genus, and possibly for that reason also the most variable in colour pattern.

Distribution
Trinidad and Brazil (PI, MT, ES, SP, PR, SC) ( Figure 8A). The vast majority of the records are from the rainforests of southern and south-eastern Brazil, but this might be merely a consequence of more intense sampling effort in those areas.   Figure 5B).

Variation
Fore wing 5.10-6.35 mm long. Antenna with 26-27 flagellomeres; gena sometimes dorsally blackish, but never reaching anterior margin of eye; area in front of anterior transverse carina of propodeum sometimes dark, blackish; brown areas of metasoma sometimes darker, blackish, always darker basally.

Comments
Very similar to L. exius sp. nov., from which it can be differentiated mainly by having 12 teeth on the ventral valve of the ovipositor (versus six), and by the colour pattern of the mesosoma, with T2 having white areas laterally (versus entirely dark brown), T3 dark brown (vs. white), and T4 white (versus dark ferruginous). Additionally distinguished from L. exius by the gena mostly white (versus completely black), scutellar carina distinct only on anterior 0.3-0.4 of scutellum (versus 0.5-1.0), and dorsolateral carina of T1 moderately strong (versus weak).

Material examined
Colour. Head black and whitish, mesosoma and legs ferruginous, metasoma dark brown and white. Head: black; scape dark ferruginous (117,072,041); pedicel with elongate white spot, remainder of pedicel and base of first flagellomere ferruginous; remainder of flagellum light brown to dark brown, toward apex except for apical one lighter; dorsal portion of apex of f4, f5-9 and base of f10 white; clypeus, ventral portion of supraclypeal area, mouth parts, base of mandible and malar space, frontal and vertical orbit whitish (234,219,186); ventral portion of gena dark brown; apex of mandible and transverse mark on supraclypeal area dark brown to blackish. Mesosoma: ferruginous (142,091,067); propleuron, collar, short dash on dorsal pronotum, subalar ridge, dorsal division of metapleuron, lateral division near hind coxa, small transverse marks over propodeal crests whitish. Legs: fore and mid coxa, fore trochanter and hind tarsi except for apical one brownish, white; hind coxa with fore portion ferruginous, hind portion white, lateral part with a broad brown mark, darker towards apex; mid and hind trochanter marked with white and dark brown; fore and mid trochantelli, femur, tibiae and tarsi ferruginous; hind trochantellus marked with ferruginous and dark brown; hind femur yellowish (211,060,129), with a darker median longitudinal line; hind tibia greyish-brown. Wings hyaline, fore wing with small, pale darker spot covering apical part of cells 2 + 3M and 1 + 2R. Metasoma: Dark brown, apical 0.2 of T1, T2 laterally, most of T3, T4-6 laterally and T7-8 dorsally, white; ovipositor reddish orange (119,074,046); sheath dark brown.

Variation
Fore wing 4.39-5.29 mm long. Antenna with 21-26 flagellomeres; gena sometimes partially black; mid coxa sometimes with dark brown spot; T1 sometimes smooth on lateral anterior portion. Two of six studied specimens with hind wing vein 2-1A distinct, reaching 0.5-0.7 of the distance to wing margin.

Comments
This is the only species of Loxopus without a distinct brownish mark on the fore wing. Very similar to L. tenuis, from which it can be differentiated by having the supra-clypeal area with distinct brownish marks (versus entirely whitish, rarely with fuscous lateral marks); posterior transverse carina of propodeum complete (versus usually incomplete); anterior portion of T1 blackish (versus orange), T3 anteriorly blackish (versus entirely white); dorsal valve of ovipositor without nodus (versus with weak nodus); and ventral valve with eight teeth (versus five). In addition, some specimens of L. duckei are the only members of Loxopus with a developed hind wing vein 2-1A.

Variation
Fore wing 3.67-4.83 mm long. General tone of ferruginous ranging from bright, almost orange (212,157,093), to almost fuscous (152,102,050); antenna with 21-27 flagellomeres; white band at flagellum sometimes starting only on f5; mesosternum sometimes entirely blackish; scutellum in some specimens the same colour as mesosoma; postscutellum whitish in specimens with general lighter colour; pro-and mesosternum sometimes with black marks; T1 white on posterior 0.25-0.40 T2 sometimes basally ferruginous; basal dark mark at T3 sometimes indicated only by a buff, ferruginous area; T3 sometimes with semicircular dark spot at apical 0.6; T4 white in one specimen.

Comments
Very similar to L. dodecius sp. nov., from which it can be differentiated mainly by having six teeth on the ventral valve of the ovipositor (versus 12) and by the colour pattern of the metasoma, with apex of T2 dark brown (versus lighter, whitish laterally), T3 white (versus dark brown with apex whitish), and T4 ferruginous (versus white). Additionally distinguished from L. dodecius by the gena black until anterior margin of eye (versus partially to completely white), scutellar carina distinct on 0.5-1.0 of scutellum (versus 0.3-0.4) and dorsolateral carina of T1 weak (versus moderately strong).

Male
Unknown.

Variation
Fore wing length 4.20-4.50 mm; one paratype with ventral 0.1 of gena yellow; one paratype with ovipositor apex with eight oblique ridges.

Comments
Generally similar to L. duckei and L. tenuis, from which it can be differentiated by having the gena almost entirely black (versus ventrally orange); subalar ridge moderately wide, elliptic (versus narrow, dash-like), and bright yellow (versus ferruginous or whitish). Further differentiated from L. tenuis by having the anterior portion of T1 blackish (versus orange), and from L. duckei by having the fore wing with distinct brownish spot (versus fore wing without spot).

Etymology
Latinized form of the type locality name, Rio Ichilo.

Male
Similar to the female, except for the following: posterior portion of vertex and occiput orange; antenna with 25 flagellomeres; f7-14 lighter than remaining flagellum but not quite white; fore and mid coxae without brown marks; hind femur without distinct brown stripe; hind tibia and basal 0.5 of T1 blackish; S1 ferruginous; anterior blackish mark on T3 covering 0.6 of its area, anterior whitish area of T4 covering 0.8 of its area; SWL 1.46; T1LW 2.62; T1WW 1.50.

Variation
Holotype and paratypes described by Kasparyan and Ruíz-Cancino (2005) with the following variation: antenna with 25 flagellomeres; scutellar carina distinct on about 0.4 of scutellum; white band on flagellum starting on f4. The illustration provided by those authors does not show the conical shape of the sublateral crests, but they are described as being 'rather strong'. The female described as L. m. honduras has T3 completely whitish; T4 predominantly black, laterally and on basal 0.2 whitish; T5-6 entirely blackish; hind tarsus white with t5 brownish dorsally; and fore wing vein 2-M distinctly shorter than 3-M.

Comments
Quite distinctive among other species of the genus by its generally stout body structure (see Figure 4B), posterior transverse carina of propodeum represented only by conical apophyses (versus well developed, complete or almost so in all other species), and ovipositor quite slender (versus moderately stout in other speciessee Figure 7H). It is also one of the two species with a complete orbital band, along with L. venezuelanus, from which it can be readily distinguished by the shape of the posterior transverse carina of the propodeum and by the hind femur with a brown stripe along the anterior face (versus fuscous with brownish marks on base and apex); T1 anteriorly black (versus orange); and T4 anteriorly whitish (versus entirely blackish). ovipositor straight; dorsal valve without nodus, preapical notch indistinct, ventral valve tip with 10 oblique ridges ( Figure 6D).

Unknown.
Comments Similar to L. duckei, from which it can be differentiated by the orbital band complete (versus widely interrupted and dorsal portion of gena); subalar ridge moderately wide, elliptic (versus narrow, dash-like), and bright yellow (versus ferruginous or whitish); transverse furrow at base of propodeum with distinct striae (versus almost indistinct); juxtacoxal carina present (versus absent); and T1 anteriorly orange (versus blackish).

Etymology
Latinized form of 'of Venezuela'; in reference to its type locality in Venezuela.

Material examined
Holotype ♀ from VENEZUELA, San Esteban, nr. Puerto Cabello, 20 January 1940, P.J. Anduze (AEIC). Apical two thirds of both antennae and right hind leg apicad of trochanter missing; otherwise in good shape.