Ischnocnemis Thomson, 1864

Eya, Bryan K., 2024, Revision of trachyderines related to Sphaenothecus from North America with description of three new genera, and new species of Lophalia Casey, 1912, Mannophorus LeConte, 1854, and Ischnocnemis Thomson, 1864 (Coleoptera: Cerambycidae: Cerambycinae: Trachyderini), Insecta Mundi 2024 (61), pp. 1-94 : 53-54

publication ID	https://doi.org/10.5281/zenodo.14662132
publication LSID	lsid:zoobank.org:pub:5671A77B-2ECB-445F-8F61-246A9E442CDE
persistent identifier	https://treatment.plazi.org/id/038487F8-026C-FF87-FF14-0D41FD09FB3A
treatment provided by	Felipe
scientific name	Ischnocnemis Thomson, 1864
status

Treatment

Ischnocnemis Thomson, 1864 View in CoL

Type species. Ischnocnemis costipennis Thomson, 1864 View in CoL (monobasic).

Ischnocnemis Thomson 1864: 199 View in CoL , 430; Lacordaire 1869: 185; Bates 1880: 83; Linsley 1935: 101; Monné 1994: 64

Redescription. Form small to moderate sized, sides subparallel. Head with front short, convex, vertical to subvertical, mid-cranial sulcus (median line) narrow, canaliculate or well defined, extending arcuately over from postclypeus to posterior margin of antennal tubercles, each side above postclypeus and below antennal insertion usually with a small, deep pit, frontoclypeal sulcus transversely excavated in middle between pits; genae short, anterior margins of lower eye lobes almost contiguous with base of mandibles, integument in between very narrow; palpi short, subequal, last segments not expanded, apex truncate, outer edge of maxillary palpi convex, usually not impressed on sides; mandibles retracted, sides strongly angulate near base then arcuate to apices, dorsum vaguely impressed on outer edges; apices simple, not emarginate; eyes moderately large, finely faceted, upper lobes small, well separated, lower lobes large; antennal tubercles moderately prominent, elevated; integument between tubercles barely impressed; antennae elongate, 11-segmented, 11 th antennomere slender, vaguely to non-appendiculate. Pronotum as broad as long to slightly broader, narrower than base of elytra at humeri, sides rounded, unarmed; apex narrower than base, apical margin with lateral collar-like projection absent; prosternum with intercoxal process level with coxae or slightly impressed between coxae, narrower than coxal cavity, apex vertical and concave behind, coxal cavities wide open behind; mesosternum with intercoxal process level with coxae, gradually declivous and usually excavate anteriorly; posterior-lateral margins lobed, slightly overlapping mesocoxae. Scutellum triangular or cordate, as broad as long. Elytra with apices truncate, each elytron with or without two longitudinal, narrow, glabrous costae or ivory-like vittae. Legs moderately short; metafemora falling far short of elytral apices in both sexes; metatarsomere I elongate, longer than or subequal to tarsomeres II and III combined. Abdomen normally segmented.

The following species are included in this genus: Ischnocnemis caerulescens Bates ( Fig. 245–309 View Figures 245–268 View Figures 269–272 View Figures 273–284 View Figures 285–296 View Figures 297–309 ), 1885; I. costipennis Thomson, 1864 ( Fig. 310–332 View Figures 310–324 View Figures 325–332 ); I. eyai Chemsak and Noguera, 1997 ( Fig. 333–345 View Figures 333–345 ); I. glabra Chemsak and Linsley, 1988 ( Fig. 346–358 View Figures 346–358 ); I. sexualis Bates, 1885 ( Fig. 359–381 View Figures 359–375 View Figures 376–381 ); I. similis Chemsak and Noguera, 1997 ( Fig. 382–395 View Figures 382–395 ); I. edmundi Eya new species ( Fig. 396–408 View Figures 396–408 ); and I. brevis Eya new species ( Fig. 409–427 View Figures 409–427 ).

Discussion. According to Bates (1880: 83), Ischnocnemis Thomson “is closely allied to Mannophorus LeConte ” with chief differences being the elongate form, longer antennae, longer “basal tarsomere of metatarsi, and attenuated and pointed apex of scutellum.” However, Bates (1885: 328) subsequently noted in his comment for Ischnocnemis costipennis Thomson that Mannophorus forreri Bates also shared the longer antennae in males, and “the scutellum was not always prolonged into a sharp point” in Ischnocnemis . Therefore, Bates concluded that “there remained no other character of sufficient importance to separate” the two genera and suggested that the name Mannophorus “will have priority” if they were to be united.

Ischnocnemis is characterized by the following combinations of characters: (1) overall form that is usually narrow and elongate; (2) front that is convex, subvertical ( Fig. 270 View Figures 269–272 , 352 View Figures 346–358 , 371 View Figures 359–375 , 402 View Figures 396–408 ) or vertical ( Fig. 327 View Figures 325–332 , 339 View Figures 333–345 , 390 View Figures 382–395 , 419 View Figures 409–427 ) with frontoclypeal sulcus deeply, transversely excavated above postclypeus; (3) mid-cranial sulcus that is arcuate from postclypeus over to the antennal tubercles; (4) dorsal half of genae that are usually narrow with anterior margin of lower eyes almost contiguous with the base of mandibles ( Fig. 271 View Figures 269–272 , 326 View Figures 325–332 , 338 View Figures 333–345 , 351 View Figures 346–358 , 370 View Figures 359–375 , 389 View Figures 382–395 , 401 View Figures 396–408 , 418 View Figures 409–427 ); (5) mandibles that are retracted and strongly angulate near base ( Fig. 270 View Figures 269–272 , 327 View Figures 325–332 , 337 View Figures 333–345 , 352 View Figures 346–358 , 371 View Figures 359–375 , 390 View Figures 382–395 , 402 View Figures 396–408 , 417 View Figures 409–427 ) as in Lophaliamorpha Eya new genus; (4) mesosternal intercoxal process that is level with mesocoxae and declivous anterior ( Fig. 272 View Figures 269–272 , 329 View Figures 325–332 , 341 View Figures 333–345 , 354 View Figures 346–358 , 375 View Figures 359–375 , 392 View Figures 382–395 , 404 View Figures 396–408 , 423 View Figures 409–427 ); and (5) first tarsomeres of metatarsi elongate, narrow and longer than or subequal to the following two tarsomeres together.

Ischnocnemis has a narrowly margined apex of pronotum as in Mannophorus but lacks the lateral collar-like projection as described by LeConte (1854: 442). Mannophorus has a front that is declivous in the middle, and antennal tubercles that are divergent with the integument between tubercles impressed forming a V-shaped valley sloping down to the mid-cranial sulcus. Mannophorus has dorsal half of genae that are usually broader with lower eyes well separated from the base of the mandible. Mannophorus minor (Bates) new combination is the only species with a narrow genae and mandibles that are more retracted and strongly angulate near base as in Ischnocnemis ; however, in this species the front is declivous in middle, and there are lateral collar-like projections on the apices of pronotum. Amongst the Ischnocnemis species I . caerulescens Bates, I. edmundi Eya new species, I. sexualis Bates , and I. brevis Eya new species have tarsomere I of metatarsi that are subequal to the following two tarsomeres combined ( Fig. 309 View Figures 297–309 , 379 View Figures 376–381 , 408 View Figures 396–408 , 427 View Figures 409–427 ). Other Ischnocnemis species with glabrous subsutural and submarginal ivory costae (i.e., I. costipennis Thomson , I. eyai Chemsak and Noguera , I. glabra Chemsak and Linsley , and I. similis Chemsak and Noguera ) have elongate metatarsi with tarsomere I that are longer than the following tarsomeres II and III combined ( Fig. 332 View Figures 325–332 , 345 View Figures 333–345 , 358 View Figures 346–358 , 395 View Figures 382–395 ).

Both Ischnocnemis and Mannophorus have the mesosternal intercoxal process that is level with coxae and gradually declivous anteriorly, and the posterior margin of the process that is discontinuous with the anterior margin of metasternum. In Lophalia and Lophaliamorpha the mesosternal intercoxal process is protuberant above coxae, and the posterior margin of the process is continuous with metasternum separated by a suture. This sternal characteristic of Lophalia and Lophaliamorpha is shared with Pleuromenus (i.e., Pleuromenus baccifer Bates and Chemsakia semicostata (Bates)) as described by Bates (1872: 194), “ Mesosternum inter coxas valde elevatum, antice veticale, postice processu metasternali continuatum, sutura separatum ” or “mesosternal intercoxal process very elevated, front vertical, behind the process continues to metasternum with suture separating.”

The genus name Ischnocnemis is Greek for “slender tibia” where ἰσΧνός, (ischnós) is “slim or slender” and Κνημίς (knēmís) is referring to the “shin or tibia”.