Bioacoustics of Philmontoides wau

Comments. P. wau is one of 8 species grouped by Ingrisch (2022) into the genus Philmontoides Ingrisch, 2022 . Type species of this genus is Lobaspis hageni Dohrn, 1905 . For Philmontoides wau the male holotype was chosen from among specimens collected by GKM and DEK: Papua New Guinea ( PNG ), Morobe Province , Wau, 12 viii 1981 , leg. G.K. Morris, [recording designation 81-2]. Depository: Naturalis Biodiversity Center, Leiden (NBC). Specimens found only on Pandanus [GKM]. Tremulation. Substrate signalling, observed as tremulation (body oscillations with or without impact, imparting vibratory substrate waves to a plant perch) is widespread among tettigoniids (e.g., Morris 1980 , De Luca & Morris 1998, Hill 2008 ). A male and female of P. wau were placed together onto a Pandanus leaf where the male engaged repeatedly in tremulation bouts. Stridulation. — To a human listener the song is a regular repetition of faint crackles, resembling a stereotyped precise static, so faint you must be very close to hear. The calls are relatively intense in the ultrasonic. Song parameters are averaged from recordings of two different singers. Based on the time domain being widely spaced short sinusoid ultrasonic pulses, this is an elastic uncoupled stridulation. The carrier is a fairly high-Q ultrasonic frequency, peaking at 26.9 kHz ( Fig. 58C, E ). Calls repeat at a rate of about 11/s near 20°C; each call consists of a train of identical 4–8 time-separated sinusoid pulses ( Fig. 58D ) comprising a major pulse train. A faint (putative opening) sound/train occurs before each intense (putative closing) train. Philmontoides has a genus-diagnostic file form (figured by Ingrisch Fig.12H ), a region of perhaps non-functional teeth extending over the file’s distal third. This leaves just 15 or so broad, distinctly spaced, teeth available to make the several ~7-wave 27-kHz sinusoids, which suggests some reversals of scraper direction during a train, i.e., there are not enough teeth on a one-wave one-tooth basis to complete one whole pulse train on one closure.

Diagnosis. With regard to the male abdominal appendages, P. wau sp. nov. resembles P. affinis ( Willemse, 1966 ) and P. commodus sp. nov. It differs from P. affinis by the extensions of the tenth abdominal tergite that are stout and curved instead of being narrow and pointing straight below and from P. commodus by the down-curved and strengthened instead of dorso-ventrally compressed and flattened extensions. From both species it also differs by thinner and more delicate, spined projections of the male cercus. Of characteristic shape are also the male titillators of P. wau that have the apical area bent in a 90° angle against the thin basal stem, are strongly elongated forming a membranous but darkened semi-roll carrying on one end a serrulate, darkened rim. That structure remotely resembles a more basic shape of titillators as found in P. hageni ( Dohrn, 1905 ) . A unique feature within the genus is also the shape of the stridulatory file on underside of the male left tegmen, which has more than the apical third of the file reduced to minute teeth that are probably not used for stridulation. The main part of the file carries teeth of medium size, not as stout as in P. hageni and related species. The female subgenital plate is so far unique as it carries a pair of shallow grooves in the apical area of the plate while in other species of the genus such grooves can be found in anterior area of the plate, or they are without any grooves. The anterior margin of the subgenital plate carries a huge widening that is however in not well-preserved specimens often hidden under the preceding sternite ( Fig. 17P ). The lateral margins of the subgenital plate are little narrowing posteriorly; in less well-preserved specimens or collected when still soft the plate may have shrunk and appear to have parallel lateral margins, but the apical grooves are distinct; the very base of the plate in these specimens is hidden under the preceding sternite but the lateral expansions are usually still visible on both sides of the hidden area ( Fig. 17O ).

Description. Elongate species with tegmen reaching to about end of hind femur ( Fig. 9C ). Pronotum elongate, disc with anterior margin rounded, often faintly concave in middle, posterior margin broadly rounded. Prosternal spines long; mesosternal lobes obtuse; metasternal lobes rounded and with an angle or fold. Femora with the following number of spines on ventral margins: (1) 4-7 / 2-9, mostly 6-7; (2) 0-7, mostly 5-6 / 1-7, mostly 2-3; (3) 7-12, mostly 9-10 / 5-15, mostly 9-10 (n = 38); hind knee lobes with two apical spines on both sides; five specimens have also the anterior knee lobes on one or on both sides with two spines. Male. Stridulatory file ( Fig. 12H ) in about basal two thirds with large and spaced teeth; after a sinusoidal step, teeth abruptly narrowing and becoming denser and hardly perceptible toward end; stridulatory file total length including uncountable teeth at end 1.08–1.33 (mean 1.24) mm; area with countable teeth 0.94–1.20 (mean 1.10) mm with 34–55 (mean 45) teeth, area with large teeth including step 0.70–0.95 (mean 0.85) mm with 19–34 (mean 27) teeth, area with largest teeth 0.55–0.69 (mean 0.63) mm with 14–19 (mean 17) teeth (n = 9). Tenth abdominal tergite strongly convex; anterior margin rounded, in middle slightly concave, on disc with a slight medial furrow; hind margin in more dorsal area concave and extended into a pair of curved projections that become conical and downcurved toward end, thus embracing an oval interspace with open end ( Fig. 11I ). Cerci rather short, only at very base nearly cylindrical, afterward widening with convex external and strongly concave internal surface; dorsointernal margin with a triangularly projecting process that terminates into a finger-shaped and little curved projection with a small, acute spine at tip; latero-ventral area of cercus widened in about apical half to a wide, compressed lobe with rounded rim, concave internal and convex external surface; from internal-apical margin of that lobe arises at end a narrow, finger-shaped and little curved process with a small in-curved spine at end ( Fig. 10D ). Epiproct rounded or triangularly rounded with two large lateral swellings and a medial furrow. Paraprocts compressed, with concave external surface and internal margin swollen. Subgenital plate with anterior margin triangularly excised, ventral surface with a very fine medial carinula, lateral margins in ventral view in about basal half convex, in apical half concave, but roundly upcurved in both areas and at dorsal end curved laterad, thus forming compressed dorsolateral rims; apical margin of disc roundly excised forming a pair of little conical, moderately long projections that carry rather long styli at end. Titillators with baso-central area forming a pair of compressed and elongate clasps that in basal area are curved laterad and slightly widened with rounded end; at apical end titillators laterally continued into rather narrow bands with little widened base, strongly narrowing thereafter, at end widening to a semi-disc shaped plate with darkened rim, finely serrulate margin and granular surface; from more basal margin of apical area of each titillator arises a compressed, membranous projection with granular and in part strongly hairy surface; on distal side near transient zone between central and apical area of titillators with a bunch of long bristles; membranous cover of distal areas of titillators with large dark dots ( Figs 15I–K ). Female. Last abdominal tergite furrowed and apex short conically projecting at both sides of furrow. Subgenital plate with very base of central area in most specimens at hand hidden below apical margin of last abdominal sternite. At very base of subgenital plate on both sides with a sclerotized process standing vertically to main surface of the plate and terminating laterally into a short, projecting cone; main part of subgenital plate with more or less converging lateral margins; apical area with a pair of oval impressions separated by a fine medial carina; apical margin bi-triangular with angles obtusely rounded ( Fig. 17P ). In less well-preserved specimens, main area of plate in ventral view parallel-sided or nearly so, with a fine medial carina, a pair of oval impressions in apical area, and upcurved lateral margins; apical margin with rounded lateral angles ( Fig. 17O ). Coloration. Face of general color, antennal scrobae light or darkened, internal surface of scapus and fastigium verticis brown or black; vertex, occiput and upper area of genae black or dark brown but posterior area of vertex often of light general color. Pronotum with dorsal surface of general color, in posterior area with indication of a dark medial band along a weak carina, lateral lobes black with one or two light spots, margins black but partly of light color; tegmina along anterior and posterior margins of light color, partly with dark spots, in central area dark brown with light veinlets, radius and media brown, cubitus cu1 thickened and at least in basal area black; cu2 of light color; all these veins getting lighter toward apical area. Hind femur with black pre-genicular ring. Measurements ( 22 males , 17 females ).—Body w/wings: male 33–37, female 35–39; body w/o wings: male 25–32, female 25–32; pronotum: male 6.5–9.0, female 6.5–8.2; tegmen: male 23.5–27.0, female 25.5–29.0; hind femur: male 20.5–23.5, female 20.5–23.0; antenna: male>60–140; ovipositor: female 14.0– 16.5 mm .