Horaiella pectinata, Curler & Priyadarsanan & Atree, 2015

Curler, Gregory R., Priyadarsanan, Dharma Rajan & Atree, 2015, Descriptions of Psychodidae (Diptera) from the Western Ghats of India, Acta Entomologica Musei Nationalis Pragae 55 (2), pp. 473-483 : 475-477

Horaiella pectinata sp. nov.

Type material. HOLOTYPE: J, INDIA: KERALA: Wayanad, Vythiri Resort , near small stream, 1.–19.ii.2007, coll. M.E. Irwin (Malaise trap); deposited ZSI-WGRC (No: ZSI/ WGRC /IR/IV/4471).

Diagnosis. Male. A small Horaiella , total length 0.99. Palpus 3-segmented; wing length less than 2 mm, radial fork arising basal to the apex of R 2+3, medial fork arising at level of R 2+3 apex; terminalia with gonostyli gradually curved at base and apex, 9 th tergum with lateral lobes digitiform, directed posterolaterally; cerci each with row of conical setae inserted posterodorsally, appearing pectinate.

Description. Male ( Figs 1–5 ): Measurements (n=1): head height 0.26; head width (not measured); wing length 1.67; wing width 0.47; head with transverse row of ten elongate, rigid setae inserted anterodorsally; eyes rounded, dichoptic, widely separated; antenna with 17 articles; scape inconspicuous, about ½ the length of pedicel, slightly recessed within frons; pedicel globular; flagellomere one about 1.5× as long as f 2; f 2–12 gradually decreasing in length, f 13 appearing swollen, wider than preceding flagellomeres, f 14 slightly longer than preceding flagellomere, apical flagellomere about 1/3 the length of preceding flagellomere; f 1–12 with a single digitiform ascoid inserted ventrally to ventrolaterally about ¼ the length from apex of f 1 and mid-length on f 2–12. Palpus with three segments; palp segment two with numerous hyaline sensilla inserted posteromedially; palp segment proportions 1-1-1.5. Thorax ( Figs 1, 4 ). Wing with radial fork arising basal to the apex of R 2+3, medial fork arising at level of R 2+3 apex; branches of medial fork divergent in comparison to those of radial fork; Sc ending in R 1, R s with three branches, M with four branches. Foretibiae each with spur-like projection inserted posteroapically; spur-like projection with a row of four conspicuous setae and one smaller seta inserted distally on its medial surface.

Terminalia ( Fig. 5 ). unrotated, epandrium placed dorsally; epandrium with digitiform lobes posteriorly; lobes directed posterolaterally; gonostyli gradually curved at base and apex, sinuous in dorsal view, slightly longer than gonocoxites; cerci each with row of conical setae inserted posterodorsally, appearing pectinate, with one prominent clavate seta inserted dorsomedially; aedeagus bifurcate, branches divergent; parameres fleshy, bilobed posteriorly, encircling aedeagus.

Etymology. From the Latin adjective pectinatus, meaning “comblike, toothed” in reference to the remarkable cerci of this species; both have a row of tooth-like setae arranged in the shape of a comb.

Distribution. Recorded only from the type locality.

Comments. It is generally not advisable to describe a species based on a single specimen. In doing so, there is a greater possibility that interspecific variation will be overlooked and/ or morphology will be misinterpreted; however, in some cases there are valid reasons to take this chance. Horaiella is a taxon that is rarely collected and most species of this group are described from limited material. For H. pectinata sp. nov., the excellently preserved holotype presented a unique opportunity to adequately describe a species of this poorly known genus from a region where it was not previously known to occur. Given the unique morphology of the new species, it is impossible to confuse it with other described species. Nonetheless, collection of additional material will make it possible to understand the morphology in greater detail.

Horaiella , and consequentially Horaiellinae , previously included four described species: H. prodigiosa Tonnoir, 1933 and H. consimilis Tonnoir, 1933 from West Bengal, H. kuatunensis Alexander, 1953 from southeastern China, and H. iota Curler, 2006 from central Thailand ( CURLER et al. 2006). Horaiella pectinata sp. nov. increases the total number of described species to five. Based on the wing venation, three palp segments (as opposed to four in Himalayan and Chinese species), and the small body size (compared to Himalayan and Chinese species), H. pectinata is most similar to H. iota . Nonetheless, the aforementioned similarities are somewhat superficial given there are also marked differences in the genitalia of these two species. Most notably, H. iota does not have cerci developed for clasping, while H. pectinata does not have distinct parameres with the setose lobes found in all other described Horaiella . Lastly, the lack of torsion in the male genitalia of H. pectinata is a significant difference from the other described species.

Horaiella remains restricted to the Oriental Region; however, the significant variations in morphology among known species of this group, as well as the relatively discontinuous distribution suggest that more species remain to be discovered. Indeed, more species need to be examined before it willbe possible to characterize the subfamily adequately and determine relationships within Horaiellinae .

Figures

Fig 5. Horaiella pectinata sp. nov. male genitalia, dorsal view. Abbreviations: aed – aedeagus; crc – cerci; eja – ejaculatory apodem; epd – epandrium; gcx – gonocoxite; gst – gonostyle; prm – paramere. Scale bar 0.15 mm.

Figs 1–4. Horaiella pectinata sp. nov. 1 – wing; 2 – male head, frontal view; 3 – flagellomeres 11–15; 4 – apex of right fore tibia, with base of tarsus 1, mesal view. Scale bars: 1, 4 = 0.50 mm; 2–3 = 0.15 mm