Pteroplistes silam Tan, Gorochov & Robillard, 2024

Tan, Ming Kai, Gorochov, Andrei, Japir, Razy, Chung, Arthur Y. C. & Robillard, Tony, 2024, New species of little-known crickets from the subfamily Pteroplistinae (Orthoptera, Grylloidea) from Sabah and contribution to their bioacoustics, Zootaxa 5506 (2), pp. 205-226 : 219-221

Pteroplistes silam Tan, Gorochov & Robillard , sp. nov.

( Figs 2C , 3C , 4C , 13 , 14 , 15A )

Material examined. Holotype: EAST MALAYSIA: • ♂; Sabah State, Mount Silam, near Lahad Datu ; N4.96878, E118.17189, 736.1± 5.4 m.a.s.l.; calling on tree trunk; 12.v.2022, 21h56; M.K. Tan, T. Robillard & R. Japir leg.; SBH.22.42 ( FRC).

Diagnosis. This species is most similar to Pteroplistes acinaceus Saussure, 1877 from Malay Peninsula and Pteroplistes bruneiensis Tan, Gorochov & Wahab, 2019 from Borneo in the ectophallic fold [rachis] of the male genitalia with a pair of rather large and sclerotized processes on its dorsal surface (dp) (before the apical part) but distinguished from them by these processes thickened, almost straight and with acute apices (these processes in P. acinaceus with characteristic hooks distally, and in P. bruneiensis , they are triangular). It is also similar to P. acinaceus , P. bruneiensis and Pteroplistes lagrecai by the shapes of the anal plate having a pair of small lobules (hooks), but differs from them by the lobules spaced widely apart (instead of nearly touching each other in P. bruneiensis and Pteroplistes lagrecai ) and with the apices of the lobules slightly enlarged (instead of tapering into acute apices in P. acinaceus ). The new species also differs from congeners from India ( Pteroplistes masinagudi , Pteroplistes kervasae and Pteroplistes platycleis ) by the head dorsum without distinct pale bands behind eyes, shapes of male anal plate and male genitalia.

Etymology. The species is named after Mount Silam, its type locality.

Description. Body distinctly dorsoventrally compressed, with head and pronotum finely pubescent. Head rostrum 1.3 times as wide as scape, with apex truncated ( Fig. 13A ). Head wider than high in facial view ( Fig. 13C ). Maxillary palps elongated, with apical segment widened apically and subequal to third segment in length, and with subapical segment longest and slightly broadened apically ( Fig. 13B ). Eyes elongated in profile view, slightly protruding anteriorly ( Fig. 13B ); median ocellus small and rounded; lateral ocelli larger and more elongated; fenestrae between scapes rounded, small like median ocellus ( Fig. 13C ). Pronotal disc 1.3 times as wide as long, finely pubescent along anterior and posterior margins; anterior margin of disc concave; posterior margin of disc straight; lateral margins sub straight and parallel ( Fig. 13A ). Pronotal lateral lobe 2.1 times as long as high, with ventral margin rising posteriorly ( Fig. 13B ). TI with minute oval tympana on both sides; legs I and II generally pubescent (especially along ventral margin) and with a few stout setae usually located along dorsal margin, and their tarsus with a row of stout setae on ventral surface; FIII pubescent and flattened, without ventral spines; TIII also pubescent, with about 18 small and stout spines on each dorsal side, and with 2 long ventral apical spurs on inner margin and 4 shorter other apical spurs; hind basitarsus with about 7 inner and 7 outer denticles.

Male. Metanotal gland with two lateral areas cream coloured, broadly triangular and slightly raised ( Fig. 13A ). FW extending beyond abdominal apex, with dorsal field slightly longer than lateral field ( Figs 13D, 13E ); dorsal tegminal field ( Figs 13D, 13E ) in harp area with 6 oblique veins, mostly almost straight and parallel (except for posterior one which slightly sinuous); mirror in this field large and rounded, as wide as long, with anterior margin roundly angular, with posterior margin somewhat more widely rounded, and with two parallel dividing veins (these dividing veins arcuate and located close to one another); apical field about as long as length of mirror, separated from mirror by distinctive transverse cell ( Figs 13D, 13E ); lateral field wide, with about 20 branches of Sc and about 10 cross-veins (some veins faint) between R and M, as well as with R and M mostly parallel and strongly converging towards the apex ( Figs 13D, 13E ). Hind wings slightly surpassing FWs. Anal plate broadly tongueshaped and slightly bilobed apically, with a pair of small lobules (hooks) in central part of dorsal surface but not very near each other; each of these lobules pointing inwards and tapering into subacute apex ( Fig. 13F ). Subgenital plate trapezoidal, about as long as wide; anterior margin wide, tapers slightly posteriorly, and with posterior margin deeply emarginated.

Male genitalia as shown in Fig. 14 . Pseudepiphallus [epiphallus] almost H-shaped, with transverse but moderately long median bridge between lateral parts, moderately short posterolateral lobes and long anterolateral parts; pseudepiphallic lophi [posterolateral epiphallic lobes] lamellate, with inner margin strongly sclerotized and concave, with lateral margin distinctly convex, and with apical part forming small hook directed dorso-externally; median bridge (mb) in shape of parallelogram, with anterior margin 1.9 times as wide as long; anterolateral parts of pseudepiphallus lamellate, sinuate and divergent, anteriorly fused with rami. Ectophallic fold [rachis (= guiding rod)] very strongly sclerotized and directed almost perpendicularly downwards in relation to the longitudinal axis of genitalia, with distal half having anterior margin slightly convex, with apical third tapering into acute apex, with basal part having upper process (up) almost perpendicular to ectophallic fold (this process distally bifurcated into two short triangular lobes with subacute apices); dorsum of upper process with pair of dark lateral sclerites (dp) projecting laterally and posteriorly, these projections connect with ectophallic apodemes. Ectophallic apodemes [endoparameres] strongly sclerotized, slender, with middle parts almost touching each other, and with anterior parts in shape of long arcuate ribbons curved downwards and aside ( Fig. 14B ). Endophallic sclerite [formula (= mold of spermatophore attachment plate)] consists of three small but elongated plates (a pair of lateral oblique plates and unpaired transverse one) as well as a pair of larger and longer but oblique and isolated plates in anteroventral parts of genitalia. Rami rather short and narrow, strongly (arcuately) curved, lamellate and with anterior end tapering almost into acute apex.

Measurements. • ♂ holotype: BL = 14.4; BWL = 18.8; HL = 1.9; PronL = 3.3; PronW = 4.5; FWL = 15.3; FWW = 6.6.

Ecology. This species was found calling on a tree trunk at night ( Fig. 15A ).

Distribution. EAST MALAYSIA: Sabah: Mount Silam

Calling song ( Figs 2C , 3C , 4C ). Consists of a trill made up of long syllables irregular spaced-apart. At 23.6°C, average syllable duration is 26.8±1.1 ms (25.6–29.7 ms) and average silent interval between consecutive syllables is 115.8±40.1 ms (89.8–249.2 ms). The frequency spectrum is pure-tonal and forms a clear harmonic series, with the energy peaking at a dominant fundamental frequency of 5.34 kHz.

Figures

FIGURE 2. Power spectra of the calling songs of the pteroplistine cricket species: Tembelingiola biaculeata sp. nov. (A), Tembelingiola kabili sp. nov. (B), Pteroplistes silam sp. nov. (C), Pteroplistes lagrecai Gorochov, 2004 (D) and Singapuriola separata Gorochov & Tan, 2012 (E). The grey line represents the power [dB] (axis name and scale in grey) and the black solid peak represents the relative amplitude (axis name in black).

FIGURE 3. Oscillograms of the calling songs of the pteroplistine cricket species: three echemes with different lengths of Tembelingiola biaculeata sp. nov. (A), two echeme-sequencesof Tembelingiola kabili sp. nov. (B), continuous trill of Pteroplistes silam sp. nov. (C), an echeme-sequence of Pteroplistes lagrecai Gorochov, 2004 (D) and three echemes of Singapuriola separata Gorochov & Tan, 2012 (E). Scale bar: 1 s.

FIGURE 4. Oscillograms of the syllables of the pteroplistine cricket species: Tembelingiola biaculeata sp. nov. (A), Tembelingiola kabili sp. nov. (B), Pteroplistes silam sp. nov. (C), Pteroplistes lagrecai Gorochov, 2004 (D) and Singapuriola separata Gorochov & Tan, 2012 (E). Scale bar: 0.05 s.

FIGURE 13. Pteroplistes silam sp. nov.: head and pronotum in dorsal (A) and lateral (B) views, face in anterior view (C), left (D) and right (E) FWs in dorsal view, supra-anal plate in dorsal view (F). Scale bars: 5 mm (A, D, E); 2 mm (rest).

FIGURE 14. Male genitalia of Pteroplistes silam sp. nov. in posterodorsal (A), dorsal (B), ventral (C) and lateral (D) views, before (A) and after (B–D) cleaning with KOH. Scale bar: 1 mm.

FIGURE 15. Pteroplistes silam sp. nov. calling on the tree trunk in Mount Silam (A), and Pteroplistes lagrecai Gorochov, 2004 calling on the tree in Sepilok (B).