Madagocerum idvigun, Oláh & Johanson, 2011

Oláh, J. & Johanson, K., 2011, Description Of A New Endemic Genus Of Trichoptera From Madagascar (Odontoceridae), Acta Zoologica Academiae Scientiarum Hungaricae 57 (2), pp. 117-129 : 123-125

Madagocerum idvigun sp. n.

( Figs 5–16 )

Diagnosis – This species resembles M. bhemi sp. n. in its short segment IX, but the remaining parts of the genitalia are different. Madagocerum idvigun sp. n. has narrow, tapering and tangential preanal appendages, not broad, blunt and divergent as in M. bhemi ; segment X is as long as the preanal appendages, not shorter as in M. bhemi ; each coxopodite has an apicodorsal spiny protuberance; both harpagones are broad, not narrow as in M. bhemi ; and the phallic apparatus is more slender and narrowing apically.

Description – Male (in alcohol). Body light brown; forewing membrane light brown, without pattern (in alcohol).

Wings ( Fig. 12 ): Forewing apex narrowly rounded; 5.0 mm; membrane light brown; termen slightly convex; basal lobe covered by microtrichia; jugum absent. Forewing forks I, II, III, and V present; Sc fusing with R1; R1 fusing with R2 before C, meeting at hypertrophied pterostigma; distally almost indiscernible; Cu2 apparently absent in forewings; postanal vein running closely to posterior wing-margin.

Male genitalia ( Figs13–16 ): Abdominal segment IX fused annularly, short in lateral view; tergum almost as long as venter; anterior margin convex, with triangular pleural plate bearing mesally depressed lateral concavity in dorsal view; posterior margin straight, with tiny subtriangular apical lobe below preanal appendages; antecosta and antecostal suture, on anterior margin of segment IX narrow, forming dark marginal rim running evenly along anterior margin; acrotergite well developed, with sclerotized rim; entire surface of segment IX glabrous, spine row absent on posterior margins of segment IX, setose areas absent from apicopleural and apicoventral regions. Intersegmental depression between segments IX and X very deep, stepwise. Segment X sunk deep to upper 1/3rd of segment IX in lateral view; intersegmental depression covered by fused base of preanal appendages. Segment X very shallow, slender; deeply bilobed; slightly arching mesad in dorsal view, dorsad in lateral view. Apicoventral setose lobes represented by apex; apicodorsal setose lobes reduced to small setal areas on middle; segment X deeply cleft; dorsal interlobular gap long, almost closed in ventral view. Large, deeply bilobed preanal appendages dominating over phallic apparatus; fused basally; horizontal, posterad directed lobes fused to dorsum of segment IX; fused seam, representing borderline between segment IX and preanal appendages invisible; in lateral view, dorsum straight horizontal, venter slightly tapering; in dorsal view with individual preanal appendages, or bilobed structures, more slender than in dorsal view, tapering, weakly constricted; mesal margins parallel sided in dorsal view; almost touching along their lengths. Coxopodites robust, with protuberance on apicodorsal corner covered by stout, medium-long spines; slightly directed mesad. Harpagones large, view, 11 = mesonotum, dorsal view, 12 = right wings broad, with slightly ventrad and mesad curving spiny apical surface, spines dark, short, conical. Phallic apparatus with broad, ventrally directed, short, basal part; apical part horizontal, straight, narrowing. Small phallotremal sclerites almost indiscernible.

Material examined – Holotype: Male : “ Madagascar: Vacoana , Foret, Imatso 1550 m, 22.i.1958

[Paulian]”.

Etymology: Idvigun, from Sanskrit “idvigunn”, meaning double; referring to the similar shape of the preanal appendages and segment X in dorsal view; and the additional spiny hump on the dorsum of the coxopodites duplicate the spiny apex of the harpagones.

Figures

Figs 5–12. Madagocerum idvigum sp. n., holotype: 5 = head, frontal view, 6 = head dorsal view, 7 = right maxilary palp, 8 = tentorium, dorsal view, 9 = tentorium, lateral view, 10 = pronotum, dorsal

Figs 13–16. Madagocerum idvigum sp. n., holotype: 13 = genitalia, lateral view, 14 = genitalia, dorsal view, 15 = genitalia, ventral view, 16 – phallus, lateral view