Bioacoustics of Anthracites sineaureus

Distribution. PHILIPPINES (Mindanao: Misamis Occidental , Lanao del Norte ). Calling song ( 1♂ , 29.5°C) ( Fig. 10 ). The calling song consists of interrupted echeme trills that vary in duration. The trill is made up of a sequence of bi-syllabic echemes. The average echeme duration is 25.7±1.1 ms (23.2–28.2 ms), average echeme period is 71.5±4.6 ms (63.6–83.8 ms), and the average silent interval between consecutive echemes is 45.8±4.9 ms (37.9–58.4 ms). Each echeme is made up of two discrete syllables. The first syllable is shorter in duration and lower in amplitude than the second syllable. The average durations of the first and second syllables are 7.7±0.8 ms (6.3–9.4 ms) and 12.6±0.7 ms (11.2–14.2 ms). The average silent interval between the two syllables is 4.9±0.7 ms (3.6–6.8 ms). The call spectrum is broad band. It has a fundamental peak at 11.3±0.4 kHz (10.8–12.3 kHz) showing energy in the sonic range, and another peak at 20.3±1.1 kHz (17.9–21.3 kHz) showing energy in the near-ultrasonic range. The peaks have relatively similar energy.

Diagnosis. The new species is characterized by the male subgenital plate with a dorsal projection at the bottom of apical emargination long and at the apex forked; the male cercus stout, and at the apex rounded, its inner margin with two large processes: the dorsal process triangular with its apex having a small tooth, the ventral lobe more finger-like, slenderer, apical end truncated; and the male titillators X-shaped and wing-like, with its lateral arm pointing dorsally; having a stout hook pointing dorsad; tegmina having veins yellow brown, but lateral part without golden or cream-colored spot; dark coloration with orange sternites. The new species is similar to sympatric species A. zebra from Mount Malindang and Anthracites sebu Tan et al. , 2024 from Lake Sebu by the general coloration, male subgenital plate having a dorsal projection at the bottom of the apical emargination, and the general shape of the male titillators; but differs by the tegmen with lateral parts with yellow brown veins (instead of distinctly golden yellow or brightly cream colored); stridulatory file on the left tegmen having distinctly fewer number of teeth (ca. 54 vs. >76 teeth); the shape of its male cercus having two inner processes (instead of one); the shape of the subgenital plate dorsal projection bifurcated (instead of tapering into narrow apex); the titillators having the apical spine on the lateral arm pointing dorsad (instead of ventrad). The female of the new species is also similar to A. sebu in the tenth abdominal tergite, subgenital plate, and ovipositor, but differs by also the coloration. The new species is also similar to dark-colored congeners Anthracites major Hebard, 1922 and Anthracites inopinatus Gono & Tan, 2025 from Surigao, and Anthracites furvuseques Tan et al. , 2018 from Siargao Island; but differs by the cercus with the inner margin having a ventral process finger liked and apex truncated (instead of with acute apex), the dorsal projection at the bottom of the subgenital apical emargination longer and forked at the apex (instead of shorter, nodular, and not bifurcated), and the shape of titillators. The new species has similar titillators as Anthracites nitidus Redtenbacher, 1891 from Mindanao and cercus also having a ventral process, but this process is not slender and does not bifurcate at apex; it also differs from A. nitidus by the presence of dorsal projection on the male subgenital plate.

Description. Habitus as shown in Figs 4 , 5 . Fastigium verticis compressed laterally ( Figs 7A, 7B ), in dorsal view conical with fine longitudinal groove, lateral ocelli before middle, apex truncated, shorter than scapus ( Figs 7A, 7B ). Frons shining with very few faintly impressed dots ( Figs 6A , 7C ). Pronotum smooth to slightly wrinkled, disc broadly rounded into paranota, apical area rounded and faintly shouldered; anterior transverse sulcus short, posterior transverse sulcus longer and rounded; anterior margin truncated; posterior margin rounded ( Figs 7A, 7B ). Paranota with ventral margin broadly concave, posterior margin angularly sinuous ( Figs 7D, 7E ). Acoustic spiracle large and elongated oval, covered by paranota ( Figs 7D, 7E ). Tegmen reduced, mirror area fully covered by pronotal disc, reaching only middle of 2 nd abdominal tergite, with rounded apex ( Figs 6C , 7A, 7B , 8A ); hind wing present, but covered by tegmen ( Fig. 7A ). Prosternum with two long acute spines pointing nearly ventrad. Mesosternal and metasternal lobes conical with acute apices. Both tympana on anterior tibia slightly swollen with narrow slit ( Fig. 7F ). Anterior coxa with long and curved spine. Femora with the following number of spines on ventral margins: anterior femur 4–5 external, 6 internal; middle femur 6 external, 1 internal; posterior femur 8–10 external, 3 internal. Knee lobes of anterior and middle femora obtuse externally and spinose internally; knee of posterior femur bispinose on both sides, longer than those of anterior and middle femora. Tibiae with the following number of spines on ventral margins: anterior tibia 6–7 external, 6–7 internal; middle tibia 8 external, 7 internal. Male ( Fig. 8 ). Mirror on left tegmen small, rhomboid, about as wide as long ( Fig. 8A ). Stridulatory file on underside of left tegmen straight; about 1.1 mm long; with about 54 teeth fairly regularly spaced throughout ( Fig. 8B ). Tenth abdominal tergite at posterior margin truncated, very faintly emarginated in middle; posterior end in middle slightly depressed; depression and posterior margin with setae ( Figs 6E , 8C, 8D ). Epiproct tongue-shaped ( Figs 6D , 8E ). Cercus short and stout, dorso-ventrally compressed; distal part conical with obtuse apical protrusion; with two inner processes pointing inwards; dorsal process stout and triangular, somewhat flattened, at apex with stout tooth; ventral process smaller, slenderer, at apex flattened and widened, apical margin truncated ( Figs 6D, 6E , 8C–F ). Subgenital plate slightly wider than long, with anterior margin slightly concave, faintly converging lateral margins, apical margin deeply emarginated, emargination truncated, at middle with cylindrical projection; this projection about as wide as but surpassing lateral apical lobes, cylindrical with apical end forked, apex rounded with setae ( Figs 8C–F ). Styli stout and long, with apex rounded ( Figs 8C–F ). Titillators ( Figs 8H–K ) separate, X-shaped, and wing-like; lateral arm pointing dorsally; lateral arm slender forming the ‘skeleton of the wing’, apical end forming strongly sclerotized and stout hook with acute apex pointing dorsad; proximal of lateral arm with flattened semi-sclerotized hyalinous plate forming the ‘wing’; base with proximal end tongue shaped having rounded apex; provided with two pairs of lateral sclerites, small, slender, and slightly curved. Female ( Fig. 8 ). Tenth abdominal tergite short and transverse, at middle narrowly but deeply triangularly emarginated ( Fig. 8C ). Epiproct triangular, apex narrowly rounded ( Fig. 8C ). Cerci with apical third strongly narrowed ( Figs 8C, 8E ). Subgenital plate large, wider than long, at middle truncated ( Fig. 8D ). Ovipositor slightly stout, sabre-shaped, widest after middle; margins smooth ( Fig. 8F ). Coloration. Two color forms observed: (1) dark brown to black ( Figs 4 , 5A, 5C ) and (2) orange ( Fig. 5B ) forms. Head dorsum wholly black, or with middle part with tint of dark brown. Face always wholly black ( Fig. 2C ); scapus and pedicel black; antennae red brown; mandible black, clypeus and labrum yellow orange; maxillary palpi with segment either cream-colored or black, apical segment with apical end orange brown ( Fig. 2C ). Eyes always black. Pronotum completely black, or orange with anterior margin black (continuous to lateral lobe), and near posterior margin with two large black patches having well-defined margins shaping like triangles ( Figs 2A, 2B, 2D ). Tegmen with lateral field having veins yellow brown, cells generally black; never with infumated golden or bright-yellow spot ( Fig. 6B ); dorsal field dark or orange, translucent, veins orange or brown, mirror area lighter in coloration ( Fig. 6C ). Spine on anterior coxa orange or dark brown to black ( Fig. 2D ). Legs generally orange or brown to black; femora generally darker in coloration than tibiae, knee areas red brown; tarsi black. Tergites either dark brown or orange, slightly lighter in coloration towards apex, distal margin of each segment always black or darker in coloration; sternites orange. Tenth abdominal tergite, epiproct, cercus, and subgenital plate generally yellow brown to orange brown. Ovipositor mostly red brown ( Fig. 8F ). Measurements (in mm). See Table 1 .