Ischnocnemis costipennis Thomson, 1864

(Fig. 310–332)

Ischnocnemis costipennis Thomson 1864: 199; Lacordaire 1869: 185; Gemminger and Harold 1872: 2973 (cat.); Thomson 1878: 6 (types); Bates 1880: 83; Bates 1885: 327; Aurivillius 1912: 473 (cat.); Linsley 1935: 100 (dist.); Blackwelder 1946: 590 (cat.); Chemsak et al. 1992: 83 (cat.); Chemsak and Noguera 1993: 63 (dist.); Monné 1994: 64 (cat.); Monné and Giesbert 1994: 146 (cat.); Noguera and Chemsak 1996: 402 (dist.); Toledo-Hernández 2005: 419 (dist.)

Ischnocnemis tripunctata Blackwelder 1946: 590 (cat.)

Redescription. Male: Length 16–18 mm. Form moderate sized, elongate, narrow, slightly tapered apically; integument black, abdomen dark reddish brown, elytra with color variable, frequently dark with four eburneous costae (Fig. 312), or basal half black and gradually reddish apically (Fig. 310), or entirely yellowish brown with epipleural margins black (Fig. 314). Head small; vertex, deeply, confluently punctate with midline glabrous, vaguely carinate; front vertical, finely punctate; postclypeus with upper margin glabrous, lower half finely punctate; antennal tubercles prominent with apices angulate; genae with lower half triangular, glabrous, finely punctate beneath; pubescence on vertex, margins of postclypeus, antennal tubercles and dorsal anterior margin of genae moderately dense and obscure; labrum finely punctate, pubescence moderately dense and suberect; antennae slender, exceeding elytral apices by 2.5 to three antennomers; scape conical densely, deeply, contiguously punctate, pubescence obscure, short, erect; antennomeres II–VI cylindrical with apices enlarged, integument finely, densely punctate, obscurely pubescent with short, depressed setae, remaining antennomeres opaque, densely, minutely punctate and densely covered with minute, appressed setae with few short suberect setae on dorsum, ventral surface and apices; antennomeres from IV vaguely carinate on inner and outer surface; antennomere III longer than I; IV shorter than III, longer than I; V longer than IV, subequal to III; VI, VII, VIII, and IX subequal to V; X slightly shorter than IX; XI longest, vaguely appendiculate on apical third. Pronotum black as long as wide (L/W: 0.9–1.0), sides rounded; disc shallowly convex with five vague dorsal calli, one each on either side of anterior half, three on basal half, one longitudinally elongate, glabrous one in middle and one each on either side closer to base; punctures fine, dense, contiguous; pubescence obscure, transverse, appressed towards middle of disc; apical margin collared, narrowly constricted behind, base impressed at sides; proepisternal area rugulose, punctures shallower than disc, pubescence obscure, short, appressed towards dorsum; prosternum slightly concave, apical half transversely plicate, basal half shallowly, confluently punctate, on each side above coxae with vaguely visible, transverse, subrectangular area, pubescence long, moderately dense, suberect; mesosternum densely, coarsely, contiguously punctate on sides, punctures sparser in middle, pubescence obscure, pale, suberect; mesosternal intercoxal process as wide as coxal cavity; mesepisterna and mesepimera finely, densely punctate obscurely clothed with appressed, pale pubescence; metasternum densely punctate, densely pubescent with depressed, pale setae, integument along midline glabrate and punctures sparser, near base of mesocoxae and along periphery more densely finely punctate; metepisterna densely clothed with appressed, pale pubescence. Scutellum black, sparsely to densely punctate. Elytra 2.8–2.9 times as long as broad; each elytron with two narrow raised, glabrous costae frequently with broadly yellowish band on either side narrowing apically and attaining apical tenth (Fig. 312), and interspace in between costae with another vague, punctate costa frequently visible (Fig. 331); integument between costae densely, closely punctate, puncture finer and coalescent apically; pubescence obscure, short, suberect, and pale, setae denser and depressed apically; apices truncate, unarmed. Legs slender; femora finely, densely punctate, clothed with short, depressed setae; pro- and mesofemora slightly clavate; metafemora linear, slightly arcuate near base, shorter than body and attaining fourth abdominal sternite; tibiae densely punctate, clothed with short, depressed setae; protibiae with inner surface densely clothed with short, depressed, pale pubescence; metatarsomere I elongate, longer than tarsomeres II and III combined. Abdomen very finely, densely punctate, densely clothed with appressed pubescence, punctures and vestiture sparser in middle; apex of last sternite truncate, and vaguely emarginate at middle.

Female: Length 16–20 mm. Form slightly more robust and parallel-sided than male. Integument black, abdomen dark reddish brown or black with apices of each sternite narrowly reddish, pronotal disc with color variable, all black (Fig. 316) or usually yellowish brown with three black maculae, two on either side of apical half and one in middle of basal half (Fig. 318, 320), and occasionally with two additional narrow, oblique maculae on either side of basal half (Fig. 322). Prosternum transversely plicate on apical half as in males, more coarsely, shallowly, striate-punctate on basal half, transverse subrectangular area above coxae absent; proepisternal area with punctures coarser and denser than males. Elytra yellowish brown with epipleural margin black (Fig. 322), more frequently with black marking extending narrowly from apices to base of elytra along sutural margin (Fig. 316, 318, 320) and in between the two yellow vittate on each elytron (Fig. 316, 318). Antennae attaining apex of elytra or longer than body by one to two antennomeres, antennomeres from IV vaguely carinate on inner and outer surface or carina absent. Abdomen with apex of last sternite broadly truncate, and vaguely emarginate at middle.

Materials examined. MEXICO: Jalisco: 12.7 km NE San Gabriel, Hwy 432, 18 Oct. 1995, B.K. Eya (1 male, BKEC); 3.1 km NE San Gabriel, Hwy 432, 17 Oct. 1995, B.K. Eya (1 female, BKEC); Planta La Meza, 22.7 km N of Jct. 80 and 432, 28 Oct. 1995, B.K. Eya (1 female, BKEC). Guerrero: 10 km NW Iguala, 14 Sept. 1982, elev. 1070 m, J.A. Powell, J.A. Chemsak (1 male, 1 female, BKEC); 16 km NW Iguala 12/ 15 Sept. 1982, elev. 1160 m, J.A. Powell, J.A. Chemsak (1 male, BKEC); 23 km W Iguala, 11/ 16 Sept. 1982, elev. 1040 m, J.A. Powell, J.A. Chemsak (1 male, BKEC); 32 km W Iguala, 11 Sept. 1982, elev. 1350 m, J.A. Powell, J.A. Chemsak (1 female, BKEC); 14 km N Chilpancingo, Hwy 95 cuato, 26 Oct. 2005, B.K. Eya (1 female, BKEC). Puebla: 27 km SE Jct Hwy 115/160, 14 Oct. 2005, B.K. Eya (1 male, BKEC); MX 160, 27 km SE Cuautla, 14 Oct. 2006, F. Skillman, B. Eya (2 males, FWSC).

Discussion. According to Thomson (1864: 199) the genus Ischnocnemis, based on this type species, I. costipennis Thomson, is elongate, parallel-sided and narrowed apically with front short and concave. The antennae are slender about a fifth longer than the body, and 11 segmented with antennomere III longer than I, V slightly longer than previous, V to X subequal in length, and XI divided (or appendiculate) and longer than previous. The mandibles are robust, and prothorax is cylindrical, convex, and unarmed at sides. The elytra are elongate, shorter than the abdomen, parallel-sided with apices narrowed and truncate.

Lacordaire (1869: 185) further noted that the front of the head is short and vertical with very short genae. The antennae are barely ciliated, longer than the body, and antennomere III longer than IV, and apices of III to V knotted (i.e., enlarged or expanded apically). The upper eye lobes are well separated above. The prothorax is cylindrical and oval with base truncate and margined. The elytra are depressed along the suture, elongate, somewhat attenuated apically with apices truncate, and each elytron with two elevated costae. The legs are elongate, femora slightly clavate, and metafemora slightly exceeding the third abdominal sternite. Tarsomere I of metatarsus is slightly longer than the following two combined. The mesosternal process is wide and sloping anteriorly, and the prosternal process is much narrower and sharply arched and declivous posteriorly. Lacordaire also footnoted that Ischnocnemis costipennis was catalogued by Dejean (1835: 323) as Leptocnemus costipennis and L. tripunctatus, which were names used with uncertainty, and noted that Dejean did not provide any generic characterization of Leptocnemus. Subsequently, this species was described by Thomson (1864: 199) as Ischnocnemis with I. costipennis as the type species and L. tripunctatus as a synonymy.