Ilyobius curvata, Liu, Xingyue, Hayashi, Fumio & Yang, Ding, 2015

Liu, Xingyue, Hayashi, Fumio & Yang, Ding, 2015, Taxonomic notes of the Neotropical alderfly genus Ilyobius Enderlein, 1910 (Megaloptera, Sialidae), with description of a new species, Deutsche Entomologische Zeitschrift 62 (1), pp. 55-63 : 55

Taxon classification Animalia Megaloptera Sialidae

Ilyobius curvata sp. n. Figs 1-2, 5-11, 15

Description.

Male. Forewing length 7.0-8.6 mm, hindwing length 5.6-7.8 mm.

Head (Figs 1, 5) smoothly orange, slightly brown on clypeus, with dense short yellowish pilosity; a pair of blackish brown markings present and expanded from entire inner margins of compound eyes, with bifurcate extension medially and trifurcate extension posteriorly; raised scars indistinct. Compound eyes brown. Antennae brown. Mouthparts blackish brown.

Prothorax (Figs 1, 5) brown throughout, pronotum with anterior margin reddish brown; meso- and meta thorax blackish brown. Legs pale brown, bearing dense brownish setae; tarsal claws reddish brown. Wings smoky brown, slightly darker on costal areas and proximal portions; veins pale brown. Forewing about 2.4 times as long as wide; costal area with 13 crossveins (eight proximal ones distinct); sc-r present; Rs with two simple branches; MA with two simple branches; MP proximally fused with CuA, having simple anterior branch and bifurcate posterior branch; CuA bifurcated, CuP simple; 1A simple, 2A with two simple branches, 3A simple; three r-rs present. Hindwing slightly narrower than forewing, about 2.9 times as long as wide; costal area with seven costal crossveins (two proximal ones distinct); branching condition of longitudinal veins mostly same as that of forewing, except for MP having two simple branches; MA proximally leaving a short oblique veinlet fused with MP; M separated from R.

Abdomen blackish brown. Tergite 9 (Fig. 6) in dorsal view nearly 3.0 times as wide as long, anterior margin truncate, posterior margin slightly concaved. Sternite 9 (Fig. 7) lingulate, about twice as long as tergite 9, posteromedially slightly pointed. Gonocoxite 9 (Fig. 8) ovoid, slightly shorter than tergite 9, gradually widened posteriad, with rounded apex. Ectoprocts (Fig. 6) largely paired, ovoid, medially connected by a feebly sclerotized transverse zone. A short ovoid lobe present beneath anus (Fig. 9). Gonocoxites 11 (Figs 8-9) transversely arched proximally, median processes (= gonostyli 11) close to each other and strongly curved ventrad, with unguiform tips. Endophallus (Figs 7-8) present between tergite and sternite 9, internally with a narrow, transversely band-like, and densely scabrous membrane.

Female. Body length 9.0 mm; forewing length 9.0-9.5 mm, hindwing length 8.4-8.7 mm.

Sternite 7 (Figs 10-11) broad, subtrapezoidal in lateral view and subquadrate in ventral view, with truncate posterior margin and a small tubercular projection subdistad. Fused gonocoxites 8 (Figs 10-11) narrowly elongated, and posteriorly curved dorsad in lateral view; in ventral view nearly rhombic, longitudinally depressed as a canal from a rather narrowed posterior portion to a roundly inflated anterior portion, which is inserted beneath sternite 7; gonapophyses 8 (Figs 10-11) distinctly sclerotized, strongly convex posteriad, and widened laterally. Tergite 9 laterally separating into short, narrow dorsal region and broad, subtrapezoidal ventral region. Gonocoxite 9 (Fig. 10) broadly valvate, arcuately margined ventrad, posteriorly with a small gonostylus 9 at tip. Ectoprocts (Fig. 10) short, ovoid.

Type materials.

Holotype ♂, "Columbien [= Colombia], Moritz/ruficeps Mor[itz]. i.det. [= identified] Columb[ia]. Mor[itz]." (MFN). Paratypes 1♀, "Columbien [= Colombia], Moritz" (MFN). 1♀, "Tabernilla [ca. 9°08'N; 79°48'W], Canal Zone, Panama/May 4-07/Collected by August Busck/ Protosialis mexicana (Bks. [= Banks]) ♀, det. A. Contreras[-Ramos], [20]05" (NMNH); 2♂, Pacora [ca. 9°04'N; 79°17'W], Panama, II-19-[19]45, H.H. Stage/Plot F Sheet, 24 hrs [= hours], 45-4519/ Protosialis mexicana (Bks. [= Banks]) ♂, A. Contreras-R[amos]., det. 2005" (NMNH).

Distribution.

Colombia; Panama (Panama Province).

Etymology.

The specific epithet “curvata” refers to the strongly ventrally curved median processes (gonostyli) of the male gonocoxites 11 in the new species.

Remarks.

The new species is closely related to Ilyobius mexicana (Banks, 1901) by having similar cephalic marking patterns and general genitalic characteristics. The three paratypes of the new species from Panama were even identified to be Ilyobius mexicana by Contreras-Ramos (2008). However, Ilyobius curvata differs from Ilyobius mexicana by the male gonocoxites 11 with median processes close to each other and strongly curved ventrad and by the female fused gonocoxites 8 strongly narrowed posteriad. In Ilyobius mexicana the median processes of male gonocoxites 11 are straightly directed and the female fused gonocoxites 8 is bluntly prominent posteriorly. These genitalic differences are stable based on our examination of several specimens of both species. Moreover, concerning the body-size, Ilyobius curvata is smaller than Ilyobius mexicana , with the forewing length less than 9.0 mm in males and 10.0 mm in females, while the forewing length of Ilyobius mexicana is more than 11.0 mm in males and 12.0 mm in females.