Chaetonerius kirkspriggsi, Sepúlveda & De Carvalho, 2019

Sepúlveda, Tatiana A. & De Carvalho, Claudio J. B., 2019, Chaetonerius Hendel (Neriidae: Diptera) from the East African islands with description of four new species from Madagascar and the Comoros, Zootaxa 4567 (1), pp. 130-146 : 139-140

Chaetonerius kirkspriggsi sp. n.

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Diagnosis. Arista white with brownish base. First flagellomere short ovate with pointed apex. Antennal base absent. Face black. Area around insertion of outer vertical seta not inflated; postocular setae absent; occiput only slightly elongate longitudinally before becoming flattened in the back of the head, making the lateral occiput and back of head meet in a right angle; palpus dark brown and wide. Gena posteriorly truncated, forming a right angle in lateral view, between its ventral margin and the transverse line of the occiput. Proepisternum brown and inflated, with brown setulae and white pruinescence. Katatergite brown. Wing vein dm-cu oblique. All coxae brown.

Male. Body length 10.7 mm; conspicuous large size and dark color, with partially yellow head, thorax dorsal, pleuron and abdomen ( Fig. 16 ).

Head. Anterior margin of frons straight; fronto-orbital plate narrow and yellow with dense white pruinescence; three fronto-orbital setae equidistant ( Fig. 14 ); anterior fronto-orbital seta one fourth the length of posterior frontoorbital seta; setulae between anterior fronto-orbital seta and anterior margin of fronto-orbital plate absent; middle fronto-orbital seta thin and short, measuring less than half size of posterior fronto-orbital seta; frontal vitta mostly blackish-brown, except for median yellow stripe narrowing towards ocellar triangle; vertex blackish-brown, bordered laterally by yellow stripe with white pruinescence extending from fronto-orbital plate to occipital foramen, delineating the dark median occipital sclerite; vertex and median occipital sclerite joining to form a right angle; median occipital sclerite blackish-brown. Occiput blackish-brown with median yellow stripe; very short setulae scattered from inner vertical seta to postgena; two occipital setae in one side and three in the other; yellow postgenal setulae scattered laterally and sparse long black setulae near occipital foramen. Frontogenal suture extends anteriorly beyond parafacial reaching antennal base. Antennae. Arista covered by short pubescence; arista inserted apically; scape and pedicel together almost as long as first flagellomere.

Thorax. Blackish-brown; three dorsal longitudinal stripes of gray pruinescence, merging into one wide gray pruinose stripe postsuturally; two short dorsocentral setae anteriorly on one side of presutural scutum and three on the other. Scutellum trapezoid with curved margins; length of distal margin between scutellar apical setae, slightly longer than half the distance between prescutellar dorsocentral setae; median yellow stripe narrower than thoracic gray pruinose stripe; discal scutellar seta one third shorter than anterior notopleural seta. Pleuron mostly blackishbrown, with dorsal yellow stripe from dorsal half of proepisternal lobe to wing base, dorsal katepisternum, katepimeron and dorsal meron. Proepisternum with two yellow setulae ventrally and one spine-like seta, as long as half of anterior notopleural seta. Anepisternum and katepisternum with yellow and brown setulae posteriorly.

Wings. Infuscate around reaching point of veins R 2+3 and C; length 11.2 mm and width 2.8 mm. Legs. Fore coxa with anterolateral row of six setae. Femora brown with yellow ring on distal third; fore femur with short anteroventral and posteroventral spine-like setae; two anteroventral outstanding spine-like setae inserted in tubercles on distal third.

Abdomen. Tergites brown with two narrow dorsal longitudinal yellow stripes; sternite 6 visor-shaped and dark brown, expanded over proximal third of epandrium ( Fig. 23 ). Distal margin of epandrium, reaching anterior half of fourth abdominal segment ventrally; surstylus linear and half the length of cercus; cercus wide linear, slightly narrowing on distal half and as long as one third of epandrium; phallapodeme presents one circular row of minute spines on proximal third near the hypandrial arms and outer margin on distal third, presents a small triangular sclerotized area; pregonite linear; postgonite with rows of 2–3 spines and slightly sclerotized basally; distiphallus flattened and sclerotized, terminating in two spikes, one straight and slightly sclerotized and other completely membranous and coiled up.

Variation. Body length 7.5–11.8 mm. Occiput with six scattered occipital setae in one side. Dorsocentral seta on anterior margin of presutural scutum in one side only. Wing length 6.6–11.7 mm and width 1.9–2.9 mm. Dorsal yellow stripe in abdomen sometimes incomplete between anterior and posterior margins of tergites.

Female. Body length 8.3 mm. Arista darker at base. Fore coxa with one spine-like anterolateral seta, aligned with three non-spiny long setae. Fore femur with long setae and two prominent setae on distal third. Abdomen almost completely dark brown, with inconspicuous dorsomedial yellow stripe. Oviscape black at base, yellow medially and black on posterior third.

Type Material. (4 specimens) HOLOTYPE, Chaetonerius kirkspriggsi ♂ (1) Prov. Fianarantsoa, 7km. W. Ranomafana, 900m . 17–22 February 1990, W. E. Steiner (2) Malaise trap in small clearing. montane rain forest [ USNM, 1863] . PARATYPES, 1♂, Prov. Fianarantsoa, 7km. W. Ranomafana, 900m . 17–22 February 1990, W. E. Steiner [ USNM, 1864] ; 1♂ 1♀, Fianarantsoa Prov. Ramonafana National Park, Valbio Research Station , radio tower, S 21°15'15"E, 47°25'18", 900m, (14-01) M. Hauser, S. D. Gaimari & R. Harin'Hala, 13–22.i.2014, ex. Malaise trap [ CSCA, 2241 (dissected), 2251].

Etymology. We name this species in honor of Ashley Kirk-Spriggs, for his many contributions to the study of Diptera and his support to the development of this study and other relevant studies on African biodiversity. The epithet is a noun in apposition.

Distribution. Madagascar (Vatovavy-Fitovinany Region).

Comments. This new species has a conspicuously differentiated morphology and evident sexual dimorphism. Males are darker than females and have thicker setae. The representatives of C. kirksprigssi can reach twice the size of other small African representatives. Especially differentiated from other African species is the shape of the head, which is also very different from any other species of Neriidae , with the occiput lateral and the flattened back of the head meeting in an almost perpendicular angle. Additionally, as in other species of Neriidae with bigger size, the wing vein dm-cu is oblique.

Figures

FIGURES 16–20. Male habitus of Chaetonerius of the East African islands. 16. C. kirkspriggsi (HT); 17. C. ebejeri (HT); 18. C. alluaudi [BMSA, 1858]; 19. C. madagasikara (HT); 20. C. kotrbae (HT). Abbreviation: HT, holotype.

FIGURES 11–15. Head lateral of the holotypes of the new species of Chaetonerius. 11. C. ebejeri, detailed area below the scape showing the underdeveloped antennal base pointed by the arrow; 12. C. ebejeri; 13. C. kotrbae; 14. C. kirkspriggsi; 15. C. madagasikara.

FIGURES 21–25. Male genitalia of Chaetonerius of the East African islands, lateral and ventral views, square showing the zoomed apex of distiphallus (out of scale). 21. C. alluaudi [SANC, 1604]; 22. C. ebejeri [CSCA, 2246]; 23. C. kirkspriggsi [CSCA, 2241]; 24. C. kotrbae [USNM, 1633]; 25. C. madagasikara [USNM, 466].