Ischnocnemis caerulescens Bates 1885
Creators: name: Eya, Bryan K.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Cerambycidae
Ischnocnemis
Ischnocnemis caerulescens

description: Ischnocnemis caerulescens Bates, 1885
(Fig. 245–309)
Ischnocnemis caerulescens Bates 1885: 328; Bates 1892: 178 (dist.); Casey 1912: 332; Blackwelder 1946: 590; Chemsak et al. 1992: 83; Chemsak and Noguera 1993: 63; Monné 1994: 64 (cat.); Monné and Giesbert 1994: 146 (cat.); Noguera and Chemsak 1996: 402 (dist.); Noguera et al. 2002: 624 (dist.); Toledo-Hernández et al. 2002: 529 (dist., biol.); Swift et al. 2010: 32 (dist.); MacRae et al. 2012: 180 (biol.).
Ischnocnemis coerulescens Aurivillius 1912: 473 (species name misspelled)
Ischnocnemis cyaneus Bates, 1892 (new synonymy); Ischnocnemis cyaneus Bates, 1892: 178; Aurivillius 1912: 473 (cat.); Chemsak et al. 1992: 83 (cat.); Monné 1994: 64 (cat.); Monné and Giesbert 1994: 146 (cat.); Santos-Silva et al. 2018: 203 (dist.).
Ischnocnemis cyanea Blackwelder 1946: 590 (cat.); Chemsak et al. 1992: 83 (cat.); Noguera and Chemsak 1996: 402 (dist.).
Redescription. Male: Length 8–12 mm. Form small, elongate, narrow, slightly tapered apically; integument black to dark metallic blue, abdomen black with metallic bluish to reddish cast, elytra, dorsum of head and pronotum dark metallic blue. Head small; vertex, moderately, densely punctate with vague, glabrous carina in middle; front irregularly punctate; postclypeus sparsely punctate; antennal tubercles vaguely elevated with apices obtusely angulate; genae with lower half triangular, irregularly punctate; pubescence obscure, short erect on vertex, antennal tubercles, lateral margins of postclypeus, and dorsal anterior margin of genae; labrum finely punctate, pubescence longer than front and depressed; antennae slender, exceeding elytral apices by three antennomers; scape conical densely, coarsely punctate, pubescence obscure, short, suberect; antennomeres II–VI cylindrical, 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 apices; antennomeres from V carinate on inside surface; antennomere III longer than I; IV shorter than III, longer than I; V longer than IV, shorter than or subequal to III; VI, VII, VIII, and IX subequal to V; X slightly shorter than IX; XI longest, non-appendiculate. Pronotum cylindrical, as long as wide (L/W: 1.0), sides shallowly rounded; disc shallowly convex, dorsal callus absent, very vaguely keeled longitudinally in middle, basal half frequently with longitudinally elongate, sparsely punctate area in middle; apical margin vaguely collared, sides narrowly constricted; base vaguely impressed at sides; punctures dense, discretely to contiguously punctate; pubescence obscure, very short, erect with few longer setae near base; proepisternal area rugulose, punctures sparser than disc, pubescence obscure, sparse; prosternum flat to slightly concave, apical half transversely plicate, basal half densely, coarsely punctate, each side above coxae with vaguely visible, transverse, subrectangular, rugosely punctate area, pubescence dense, short, suberect; mesosternum rugulose, coarsely punctate in middle, punctures denser and finer near procoxae, pubescence obscure, pale, depressed to suberect; mesosternal intercoxal process as wide as coxal cavity; mesepisterna nitid, rugulose with shallow punctures, pubescence obscure, appressed; mesepimera with anterior half finely punctate, pubescence appressed, posterior half nitid, glabrous; metasternum evenly, discretely, coarsely punctate with long, depressed setae arising from each puncture, integument on either side of midline narrowly glabrous; metepisterna finely, densely, contiguously punctate, densely clothed with short appressed pubescence. Scutellum black, cordate to triangular, as long as wide, sparsely, coarsely punctate. Elytra 2.8–2.9 times as long as broad; each elytron with vague, subsutural costa, integument polished, moderately, densely, discretely punctate, punctures smaller and integument rugulose near apices; pubescence obscure, short, and suberect; apices obliquely or transversely truncate, exterior angle unarmed or minutely dentate. Legs slender; femora slightly clavate, coarsely, densely punctate, pubescence short, depressed, pubescence longer on inner surface of basal half; metafemora 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, subequal to tarsomeres II and III combined. Abdomen nitid, coarsely, discretely, punctate and clothed sparsely with depressed, pale setae, punctures and vestiture in middle sparser, sides with pubescence appressed; apex of last sternite truncate, and vaguely emarginate at middle.
Female: Length 8–12 mm. Form slightly more robust than male, parallel-sided, integument similar in color and sculpturing to males. Pronotum occasionally reddish with apical and basal margins narrowly black or entirely black. Prosternum transversely plicate on apical half as in males, basal half rugulose, evenly, densely, contiguously punctate, pubescence obscure and dense throughout; transverse, subrectangular area above coxae absent. Antennae exceed elytra by one to two antennomeres, carina on inner surface from antennomere V absent. Abdomen with apex of last sternite broadly truncate, and vaguely emarginate at middle.
Materials examined. MEXICO: Nayarit: Volcan Cebroruco vic., Jala, 27 Sept. 1991, J.E. Wappes, (2 males, EMEC). Jalisco: Estación de Biología Chamela, 14/ 23 Oct. 1986, J.A. Chemsak (2 males, 1 female, BKEC), 14 Oct. 1995, B.K. Eya (2 males, BKEC), 21 Oct. 1995, B.K. Eya (9 males, 3 females, BKEC), 23 Oct. 1995, B.K. Eya (5 males, 3 females, BKEC); 6/ 12 Oct. 1988, F.T. Hovore, on blossoms (2 males, CASC); 9/ 10 Oct. 1988, R.L. Westcott (1 male, DJHC). Morelos: 6 mi E Cuernavaca, 1 Sept. 1974, W. Hanson, G. Bohart (1 male, EMEC), 12 Sept. 1973, W.J. Hanson, B.A. Haws (1 male, EMEC); Hujintlan, 22 Aug. 1956, R. and K. Dreisbach (1 male, EMEC); Cuernavaca, 15 Aug. 1954, R.R. Driesbach (2 males, 1 female, EMEC). Puebla: El Tepenene, 10 mi SE Izucar de Matamoros, 4500′, 8 Oct. 1975, J. Powell, J. Chemsak, T. Eichlin and T. Friedlander (2 males, EMEC). Guerrero: 14 km SE Ayutla de los Libres, 25 Oct. 2005, B.K. Eya (3 males, BKEC); MX 125, Ayutla de los Libres, 25 Oct. 2005, F. Skillman, B. Eya (1 male, FWSC); MX 125, 8 km W Ayutla de los Libres, 25 Oct. 2005, F. Skillman, B. Eya (4 males, FWSC); 6 km W Veintidós, 21 Oct. 1984, F. Hovore (4 males, 1 female, CASC); Acapulco, 150 m, 19 Oct. 1989, R.L. Westcott, in flower of Tithonia sp. (Asteraceae) (6 males, EMEC); 13 km NW Iguala, 12 Sept. 1982, elev. 1220 m, J.A. Powell, J.A. Chemsak (1 female, EMEC); 16 km NW Iguala, 12/ 15 Sept. 1982, elev. 1160 m, J.A. Powell, J.A. Chemsak (1 male, EMEC); 10 km N Iguala, 27 Sept. 1994, Chemsak (3 males, EMEC); 33 km W Iguala, 27 Sept. 1994, Chemsak (3 males, EMEC); 20 km S Petaquillas, 29 Sept. 1994, Chemsak (6 males, 3 females, EMEC); 33 km W Iguala, 28 Sept. 1994, Chemsak (1, male, EMEC); km 55, 5 km SW Jct. Iguala-Taxco Hwy, 27 Sept. 1994, Chemsak (1 male, EMEC); Venta de Peregrino, H.H. Smith (1 female, EMEC); 5mi SW Tierra Colorado, 18 Oct. 1966, R.F. Smith (1 female, EMEC). Oaxaca: ca. Pinotepa Nacional, 18 km W Jct. Hwy 125/200, 25 Oct. 2005, B.K. Eya (7 males, 4 females, BKEC); 62 km W Santiago Astata, Hwy 200 19 Oct. 2005, B.K. Eya (2 males, BKEC); Los Morales, 1600 m, 3 Oct. 2005, D. Curoe (3 males, BKEC); 15 km W, Salinas Cruz, Hwy 200, 19 Oct. 2005, B.K. Eya (1 female, BKEC); 35 mW Tehuantepec, 16 Sept. 1974, G. Bohart, W. Hanson (1 female, EMEC); MX 175, 5 km N Portillo de Rayo, 20 Oct. 2005, dead tree, F. Skillman, B. Eya (1 male, FWSC); MX 200, 41 km E Pochutla, 22 Oct. 2001, F Skillman, J. Davidson (4 males, FWSC); MX 200, 62 km W Santiago Astata, 19 Oct. 2005, F. Skillman, B. Eya (5 males, FWSC); MX 190, 2km W Chiapas Microwave Rd. past Hotel Paty, 18 Oct. 2005, F. Skillman, B. Eya (1 female, FWSC); MW190/ 200, 41 km W Zanatepec, 18 Oct. 2005, F. Skillman, B. Eya (1 male, FWSC). Veracruz: Atoyac, 22 Oct. 1963, A.B. Lau (1 female, EMEC).
Also, tentatively assigned to this species are ten additional specimens from Chiapas, Mexico, 1 specimen each from Guatemala and Nicaragua, and seven specimens from Costa Rica as follows: MEXICO: Chiapas: Municipio de Cintalapa, 4–6 km NW La Cienega, 40 km NW Las Cruces, 1400 m, 1 Dec. 1980, D.E. and J.A. Breedlove (1 females, EMEC); Municipio de Cintalapa, La Mina, 914 m, 14 Sept. 1981, D.E. and P.M. Breedlove (1 female, EMEC); 9 km NW of Rio de Oro, 12 Oct. 1979, D.E. and J.A. Breedlove, Cal. Acad. Sci. Coll. (1 male, EMEC); Municipio Ocozocoatla, El Aguacero de Derna, 12 Oct. 1979, D.E. and J.A. Breedlove, Cal. Acad. Sci. Coll (1 female, EMEC); El Aguacero 21 Oct. 2001, F. Skillman, J. Davidson (1 male, FWSC); El Sumidero, 14 Sept. 1974, G. Bohart, W. Hanson (2 males, EMEC); 13 mi NE Las Cruces Jct., 20 Sept. 1973, J.W. Hanson, B.A. Haws (1 male, EMEC); Sumidero, 23 Sept. 1989, F.T. Hovore (1 female, CASC); Parque Aguacera, 27 Sept.–3 Oct. 1986, J. Wappes (1 male, EMEC). GUATEMALA: L. Conradt (1 male, EMEC). NICARAGUA: Masaya vic. Laguna de Apoyo, 23 Nov. 1992, E. van den Berghe (1 male, DJHC). COSTA RICA: Guanacaste Prov.: Est. Murciélago, P.N. Guanacaste, 100 m, 5–18 Nov. 1994, C. Cano, LN 320300_347200 #3329 (2 males, 3 females, EMEC); Est. Murciélago, 8 km SE de Cuajiniquil, P.N. Guanacaste, 100 m, 10–29 Oct. 1993, F.A. Quesada, LN 320300_347200 #2394 (1 male, EMEC); Playa Grande, 18/ 19 Nov. 1998, P.A. Opler (1, male, DJHC).
Discussion. According to Bates (1885: 328) Ischnocnemis caerulescens Bates (Fig. 245-268) is narrow, cylindrical, nitid, dark blue on the dorsum and black underneath. The thorax is cylindrical with base slightly constricted and moderately confluently and discretely foveolate (i.e., with deep small pits). The scutellum is triangular with apex not prolonged. The elytra are moderately, discretely punctate with one very vague costa on both sides and apices obtusely truncate. The antennae of females are longer than the body with the eleventh antennomere slightly longer than preceding ones. The metatarsi are short, and mesosternum is simple. The form of this species is similar to I. sexualis Bates; however, the elytra differ by not being costate. The length is 4.5 lines (9.5 mm). Bates (1892: 178) provided the distribution of I. caerulescens as Guerrero (i.e., “Dos Arroyos, 1000 ft., R. Papagaio, 1200 ft., Acaguizotla, 3500 ft., Venta del Pelegrino, Tierra Colorada, 200ft, and Hacienda de la Imagen, 4000 ft. ”). The type localities for I. caerulescens appear to be all along the HWY 95D between Acapulco and Chilpancingo in Guerrero, Mexico, especially on the 64 km stretch between Dos Arroyos and Acaguizotla (or Acahuizotla).
Subsequently, Bates (1892: 178) describes another species, Ischnocnemis cyaneus Bates from Yautepec, Morelos, which is closely allied but considered to be sufficiently distinct from I. caerulescens. Yautepec, Morelos, is approximately 264 km north of Acahuizotla, Guerrero. According to Bates I. cyaneus (13 mm), based on a single male specimen, is distinctly broader, cylindrical in form, and bright blue in color with antennae black. Head and thorax densely, coarsely, discretely punctate with posterior-median line dilated and smooth. The punctures on “the thorax wider apart” than I. caerulescens. The thorax is slender, cylindrical, and ovate. The elytra are equally discretely punctate with the longitudinal, glabrous costa on each elytron, which is not to “the slightly degree elevated.” The elytral apices are “transversely truncate, and both sutural and exterior angles nearly rectangular and equal.” The sternites are evenly and less sparsely punctate. He further notes that the elytra of I. caerulescens are “very obliquely truncate with prolonged external angles.”
Based on the materials examined, the actual distribution of I. caerulescens in Mexico ranges from northwestern states of Nayarit and Jalisco southeastward into Morelos, Puebla, Guerrero, Oaxaca, Veracruz, and Chiapas, and consist of individuals with diverse puncture density on the pronotum, and elytra with various apical shape and elevation of subsutural costae (Fig. 273–308). I have examined twelve specimens of I. caerulescens within 46–105 km of the type locality of I. cyaneus (Yautepec, Morelos) as follows: one from Hujintlan (ca. 46 km W of Yautepec); two from 6 mi E Cuernavaca (ca. 32 km N of Yautepec); and three from Cuernavaca (ca. 42 km N of Yautepec), two from Puebla (ca. 105 km E of Yautepec), and four from 16 km NW and 33 km W of Iguala, Guerreo (ca. 80 km SW of Yautepec). These twelve specimens are all like I. cyaneus in overall dimensions with transversely truncate apices of elytra (Fig. 289–291); however, they are slightly smaller in size (9–10 mm) with vaguely costate or non-costate elytra (Fig. 301–303). Also, specimens from Oaxaca (e.g., Pinotepa Nacional (Fig. 280) and La Luna, i.e., Bezark 2024, id: 66292) have elongate pronotum that is slightly longer than wide and disc with punctures wider apart as in the holotype (Bezark 2024, id: 16960). Ischnocnemis caerulescens from the same location (i.e., Chamela, Jalisco) also exhibits considerable variation in pronotal puncture density (Fig. 274–275), and elevation of subsutural costae on elytra (Fig. 298–299), where some may have widely separated punctures on pronotum and elytra without any hint of elevated costae as in I. cyaneus. Considering the variation found in forms throughout Mexico with variable puncture densities on pronotum (Fig. 273–284), varying elevation of elytral costae (Fig. 297–308), and shapes of elytral apices (Fig. 285–296), it is unlike that I. cyaneus represent a unique species different from I. caerulescens. Also, the intraspecific variation in the above mentioned characters of I. caerulescens within the same or nearby locations (Fig. 274–275, 279–280, 298–299, 304–305) precludes the possibility that I. cyaneus is a distinct species. Ischnocnemis cyaneus Bates; therefore, is synonymous with I. caerulescens Bates (new synonymy).
There are color-variants of I. caerulescens in Chiapas near Tuxtla Gutierrez, Mexico (Municipio de Cintalapa, a female, Fig. 257–258), and Guanacaste Prov., Costa Rica (Est. Murciélago, two females, Fig. 267–268) where females have red pronotum with apical and basal margin narrowly black, and integument and elytra that are aeneous to dark metallic bluish. Other specimens of both sexes from Chiapas are usually metallic dark bluish or black as those from other states of Mexico or have black pronotum. The males from Costa Rica have black or dark metallic blue pronotum with reddish overcast, dark metallic bluish elytra, and sternum reddish. In general, the punctures on pronotum of specimens from Chiapas southeastward into Costa Rica are sparser, shallower, and well separated (Fig. 281–284) compared to those from the northwest. A single male specimen from Nicaragua is entirely reddish brown with vague metallic bluish cast with vertex and front darker metallic bluish (Fig. 261–262).
description: Published as part of 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), pp. 1-94 in Insecta Mundi 2024 (61) on pages 55-60, DOI: 10.5281/zenodo.14662132