Tremellia timah Gorochov et Tan, new species

Tremellia timah Gorochov et Tan, new species

(Figs 9, 10, 24–34)

Material examined. Holotype (male): Singapore, Bukit Timah Nature Reserve, Hindhede Nature Park, secondary forest, 29 January 2012, coll. M.K. Tan & J.J.Y. Chan.

Paratypes: Singapore: 1 male, same locality as for holotype, 30 October 2010, coll. M.K. Tan; 1 male, Dairy Farm Nature Park, along Dairy Farm Loop, secondary forest, 20 January 2012, coll. M.K. Tan, R.W.J. Ngiam & W.L. Lim; 1 female, same park, along Wallace Trail, secondary forest, 10 July 2012, coll. M.K. Tan & K.H. Ong.

Diagnosis. The new species differs from all the other congeners with known males (Gorochov, 1996, 2004a, 2011) in the presence of characteristic lamellar ventral lobe at the distal part of ectoparameres, that is, its ectoparameres ventrally are without any notch at the subapical part; but in Tremellia fratercula (Chopard), Tremellia mindoro Gorochov and Tremellia minahassa Gorochov, such lobe is undeveloped or almost undeveloped, and their ectoparameres ventrally are with a distinct notch at the subapical part. Without female specimens of this species, differences of the new species from Tremellia spurca Stål, described for a single female from the Philippines, are unknown.

Description. Male holotype. General appearance typical of this genus (Figs 25, 26, 28). Head rostrum approximately as wide as scape. Pronotum pubescent, broader than long, widening posteriorly, with anterior and posterior margins of disc fairly straight. Fore tibia with inner tympanum (as in Fig. 9) large and oval (opened); outer one slightly smaller but also oval (opened); both tympana barely immersed; hind tibia with 4 pairs of rather long and movable dorsal spines (length of longest inner distal spine 1.5 mm), several distinctly shorter immovable spinules between them, and 6 rather long spurs (length of longest inner dorsal spur 2.0 mm).

Tegmina slightly surpassing abdominal apex, with 8 oblique veins in dorsal field (3 proximal oblique veins small), with mirror broader than long and having 2 dividing veins (proximal one straight, and distal one crescentshaped), with apical area rather short, with lateral field having 25 branches of Sc and 6 crossveins between R and M (Fig 29); stridulatory vein of right tegmen very weakly curved and with numerous stridulatory teeths (this vein with about 21 teeth per mm at median region; Fig. 30); hind wings hardly exposed behind tegmina (Figs 25, 26, 28). Anal plate with distal part fairly acutely rounded; subgenital plate simple, smooth, gently narrowing towards apex, and with apical part truncate and having brush of setae at each distolateral corner (Fig. 10).

Genitalia (Figs 24, 31–33): shape of epiphallus, of rami and of guiding rod typical of this genus; ectoparameres with characteristic lamellar ventral lobe at distal (subapical) part (Fig. 24); endoparameres with comparatively short apodemes; medial projections of endoparameres almost contacted (but not fused) with each other; mold of spermatophore attachment plate not long and with a pair of transverse projections narrower (shorter) and more elongate (wider) than in other congeners (Figs 31, 32).

Colouration. More or less orange with following marks: face and rostrum with yellowish median stripe having brown lateral margins, and with yellowish spots under eyes; mouthparts also yellowish; vertex with two faint lateral brown rings; pronotum grey-purple with lower halves of lateral lobes somewhat lighter (almost light brown); legs with brown patterns (hind femora with numerous oblique brown stripes on outer surface, with light band near knees, dorsally with irregular brown patterns, ventrally with carinulae brown; hind knee brown; hind tibiae with brown bands near bases of spines; spines and spurs on hind tibiae with black tips); tegminal lateral field with membranes between Sc branches semitransparent; abdominal tergites yellowish laterally, dark grey-purple dorsally; anal plate purple; abdominal sternites and subgenital plate yellowish; cerci orange.

Variations. One of paratypes with 7–9 oblique veins in dorsal field (2–3 proximal oblique veins small), with third (from base) oblique vein of dorsal field forked; some males with distal dividing vein of tegminal mirror somewhat angular; with 6–7 crossveins between R and M. Some paratypes with 3 outer dorsal spines on hind tibiae. Pattern of hind femora (especially light bands near knees) varied from weakly visible to very distinct.

Female. General appearance (Fig. 27) as in male, but dorsal tegminal field with 8 partly oblique longitudinal veins and rather regular crossveins between them only, lateral tegminal field with narrower R-M area and 11 branches of Sc, and subgenital plate slightly wider than long and with distal part broadly emarginate. Ovipositor rufous with dark apex, shorter than hind femur, not surpassing cerci, and with apical part having rather numerous but not large drilling teeth.

Measurements. See Table 2.

Etymology. The species is named after Bukit Timah Nature Reserve, Singapore.

Remarks. Calling song of holotype was recorded in-situ on 29 January 2012 at about 2048 hours. The calling song is a series of trills with frequency of 4.0–5.0 kHz (Fig. 34). Each trill lasts 0.22– 0.28 s (mean = 0.24 s) and consists of 16–20 major peaks (mean = 18). Pauses between trills last 0.54– 0.75 s (mean = 0.62 s). The southern part of Malacca is here indicated as a most western locality for the genus Tremellia Stål.