Ilyobius nigrocephalus Ardila-Camacho, Martins & Contreras-Ramos, 2021

Ardila-Camacho, Adrian, Rivera-Gasperín, Sara Lariza, Martins, Caleb Califre & Contreras-Ramos, Atilano, 2021, A reappraisal of the taxonomy of Neotropical Sialidae (Insecta: Megaloptera): with the description of a new genus from Cuba, European Journal of Taxonomy 782, pp. 21-54 : 37-40

Ilyobius nigrocephalus Ardila-Camacho, Martins & Contreras-Ramos sp. nov.

urn:lsid:zoobank.org:act:C033CC6B-32D3-4F61-9584-3329A25E4D08

Figs 11–15

Diagnosis

This species is distinguished from others of the genus by having a dark brown head and orange pronotum ( Fig. 11 ). The male sternite 9 is broadly rounded and shovel-like. The gonocoxites 9 are subtrapezoidal with posterior corners blunt. The gonocoxites 11 are elaborated, with two differentiated portions: the upper portion is posteriorly produced as lateral hook-shaped processes, and the lower portion as two narrow, arched, lateral sclerites, medially fused; in lateral view curved, elongated, and narrow with the distal part representing the gonostyli 11, which are dorsally connected to the upper portion and covered with minute spinulae. The membrane between gonocoxites 11 and sternite 9 is covered with minute spinulae. The female sternite 8 is subpentagonal, posteromedially produced into a short and blunt lobe. The gonocoxites 8 form an ovoid sclerite, located just beneath sternite 8; the bursa copulatrix is bilobed with the distal margin shallowly incised in ventral view.

Etymology

The specific epithet “ nigrocephalus ” is a combination of the Latin nigrum which means black, and the Greek κέφαλη (céfale) meaning head, alluding to the dark pigmentation of the head of this species. An adjective in the nominative case.

Material examined

Holotype ECUADOR • ♂; El Oro, 7 km, E. Piñas ; 2 Aug. 1989; L. Stange and R. Miller leg.; FSCA.

Paratype ECUADOR • ♀; same collection data as for holotype; FSCA .

Description

HEAD ( Fig. 12A–B ). Width 1.6 mm; nearly completely dark brown, ventrally light brown; compound eyes dark brown. Antenna with scape enlarged, dark reddish brown, covered with abundant light brown setae, pedicel dark brown, nearly as long as wide, flagellum dark brown with 32 flagellomeres, densely covered with dark brown setae. Frons densely setose, somewhat protuberant between antennae. Clypeus and labrum densely covered with light brown setae, anterior margin of clypeus with median concavity. Maxillary and labial palpi dark brown with abundant dark brown setae. Occiput with dark brown muscle scars.

THORAX ( Fig. 11 ). Pronotum orange, rectangular, nearly 1.5 times as wide as long, densely covered with minute, light yellow setae. Mesonotum wider than long, dark brown, densely covered with minute, light brown setae. Metanotum similar to mesonotum, but slightly narrower. Pteropleura dark reddish brown, covered with abundant light brown setae.

LEGS. Dark brown, all segments densely covered with dark brown setae; fore femur somewhat expanded and shorter than mid- and hind femur. Tibial spurs short, dark brown. Basitarsus of fore- and midleg short, as long as second and third tarsomeres together; on hind leg longer, as long as remainder of tarsomeres together. Pretarsal claws dark brown.

WINGS ( Fig. 12C ). Forewing 9.5 mm long, membrane translucent, smoky, densely setose. Venation light brown, densely covered with fine setae of the same color as cuticle. Costal field slightly expanded on ⅓ of wing length, with nine crossveins; pterostigma absent. A single subcostal crossvein. Radial space with three crossveins, RP with two branches, basal one forked near posterior wing margin. Radiomedial space with three crossveins, M forked near mid-length of wing, MA unforked, MP forked near posterior wing margin; intramedial space with two crossveins; mediocubital space with two crossveins; CuA vein forked slightly beyond level of M fork, CuP unforked; intracubital space with single crossvein. Cubitoanal space with single crossvein; area between A1 and A2 with a single crossvein, A2 forked before R fork level; area between A2 and A3 with single crossvein. Hindwing 8 mm long, with general aspect similar to forewing. Costal field narrow, with four or five crossveins; subcostal field with single crossvein. Radial space with three crossveins, RP with two branches, basal one forked near posterior wing margin. Radiomedial space with three crossveins. M vein forked near mid-length of wing, intramedial space with two crossveins. Mediocubital space with two crossveins; Cu forked near wing base, CuA forked at apex; intracubital space with single crossvein. Cubitoanal space with single crossvein. Area between A1 and A2 with a single sinuous crossvein, A2 forked near wing base.

ABDOMEN. Dark brown with abundant light brown setae.

MALE GENITALIA ( Figs 13–14 ). Tergite 8 semi-membranous, densely setose; tergite 9 sclerotized, ringshaped, sparsely covered with long setae, in dorsal view V-shaped around anal tubercle, laterally expanded; in lateral view trapezoidal with ventral half long, posteroventral side oblique, articulated to gonocoxite 9. Anal tubercle membranous; ectoproct mammilliform, elongated, setose, fused to anal tubercle. Sternite 9 sclerotized, broadly rounded in ventral view, densely setose, shovel-like in lateral view, reaching level of gonostyli 11 apex. Gonocoxite 9 sclerotized, adjacent to sternite 9, moderately setose, subtrapezoidal with posterior corners blunt and posterior margin slightly concave; gonostylus 9 absent. Membrane between sternite 9 and gonocoxites 11 covered with minute spinulae. Gonocoxites 11 elaborated, with two distinct portions: upper portion transversely elongated, with ventral margin arched and dorsal margin straight in caudal view; laterally not fused to ectoprocts; medially with fusion line somewhat distinct, in lateral view produced into lateral hook-shaped processes, extended slightly beyond level of ectoproct apex; lower portion as two narrow, arched, lateral sclerites, medially fused, with fusion line distinct; medial part representing the gonostyli 11, caudally produced, covered with minute spinulae and dorsally connected to upper portion.

FEMALE. External morphology and coloration similar to male, head width 1.7 mm; forewing 9.8 mm long, antennae with 29 flagellomeres; costal field with 12 crossveins; radial space with three crossveins. Hindwing 8.5 mm long, costal field with five crossveins; radial space with three crossveins.

FEMALE GENITALIA ( Fig. 15 ). Tergite 9 in lateral view ventrally extended, expanded and articulated to gonocoxite 9, posteroventral margin straight; gonocoxite 9 ovoid, uniformly setose; gonostylus 9 small, semicircular, posterodorsally located on gonocoxite 9; ectoproct as a small ovoid sclerite, setose. Sternite 8 in lateral view posteroventrally projected, with blunt apex, extended on gonocoxite 8 slightly beyond its mid-length; in ventral view subpentagonal, posteromedially produced into short and blunt lobe, entire surface densely covered by long setae; gonocoxite 8 in lateral view narrow, plate-like, densely setose; in ventral view ovoid, located just beneath sternite 8; bursa copulatrix moderately sclerotized, sac-like in lateral view, bilobed, with distal margin shallowly incised in ventral view; gonapophyses 8 as lateral smooth, glabrous, ovoid plates.

Distribution

Ecuador (El Oro) ( Fig. 7D ).

Remarks

Ilyobius nigrocephalus sp. nov. is related to Ilyobius ranchograndis ( Contreras-Ramos, 2006) from Aragua, Venezuela because of the complex morphology of the gonocoxites 11 of the male, as well as the structure of the female genitalia (see Contreras-Ramos 2006). Both species lack the posteriorly trifurcate dark marking around the compound eyes, having the head uniformly colored. However, the new species has the head nearly completely dark brown, with some muscle scars on the median area of the vertex, while I. ranchograndis has the head orangish brown. Furthermore, the pronotum of I. nigrocephalus sp. nov. is uniformly orange, whereas in I. ranchograndis it is orangish brown with darker margins. Ilyobius nigrocephalus sp. nov. is known from two specimens from El Oro province of Ecuador, which is located in the geographical area known as the coastal region, with its northwest region limited by the Pacific Ocean. Rivers in El Oro Province originate in the Andean Mountains and flow into the Gulf of Guayaquil. The climate of this mountainous region where the specimens were collected is rainier and colder compared to the coastal region.

Figures

Fig. 11. Holotype male of Ilyobius nigrocephalus sp. nov., dorsal habitus.

Fig. 12. Holotype male of Ilyobius nigrocephalus sp. nov. A. Head, dorsal view. B. Head, dorso-frontal view. C. Fore- (above) and hindwing (below).

Fig. 13. Holotype of Ilyobius nigrocephalus sp. nov., male genitalia. A. Lateral view. B. Morphological interpretation of genital sclerites in A. C. Laterocaudal view. D. Morphological interpretation of genital sclerites in C.

Fig. 14. Holotype of Ilyobius nigrocephalus sp. nov., male genitalia. A. Dorsal view. B. Morphological interpretation of genital sclerites in A. C. Caudal view. D. Morphological interpretation of genital sclerites in C.

Fig. 15. Paratype of Ilyobius nigrocephalus sp. nov., female genitalia. A. Lateral view. B. Morphological interpretation of genital sclerites in A. C. Ventral view. D. Morphological interpretation of genital sclerites in C.

Fig. 7. Distribution of species of Sialidae (Megaloptera) studied herein. A. Distribution of Caribesialis bifasciata (Hagen, 1861) comb. nov., Ilyobius bimaculatus (Banks, 1920), and I. nigrocephalus sp. nov. B. Distribution of C. bifasciata comb. nov. in Cuba. C. Distribution of I. bimaculatus in Bolivia. D. Distribution of I. nigrocephalus sp. nov. in Ecuador.