Bioacoustics of Xenogryllus marmoratus

Redescription. Species of small to average size, the smallest for the genus ( Fig. 1 E–G). Coloration almost homogeneously light ochre. Median dark band on head dorsum faint on vertex ( Fig. 4E ), prolonged anteriorly by black fastigium, with three narrow lateral bands on each side. Fastigium straight, not widened anteriorly. Antennae light brown, first segment darker. Face relatively flat in lateral view ( Fig. 3J ). Pronotum dorsal disc light brown, with a median brown band variably marked prolonging head coloration; lateral margins not carinated, with a narrow yellow line; lateral lobes ochre, progressively lighter ventrally. Male. FWs light brown, translucent ( Fig. 5E ); dark coloration anterior to 1A sometimes extended on angle of 1A. Transverse part of file almost straight, with 435 stridulatory teeth (n=1) on transverse part of 1A. Harp as wide as long. Fused part of cells c1 and b1 as long as individualised part of c1. Cell d2 wider than in other species. Mirror wider than long, little rounded, its inner limit forming a wide angle. Apical field short, including five cell alignments. Male genitalia ( Fig. 7 H–I): Pseudepiphallic sclerite longer than rami; pseudepiphallic lophi very long ( Fig. 8G ), narrow and sclerotized, slightly convergent, ended by an apical lamella curved dorsally and forming a small notch. Pseudepiphallic sclerite with wide lateral membranous lobes. Basal reinforcement of pseudepiphallic sclerite strong. Rami short with convergent hook-like apex. Pseudepiphallic parameres with a ventral transverse crest absent in other species; inner apex of of pseudepiphallic parameres sharp, slightly sclerotized apically. Ectophallic apodemes strong, not lamellate. Ectophallic lateral arms strong, fused to lateral arms of ectophallic fold, and with lateral arms of endophallic sclerite, forming together a wide gutter. Ectophallic fold entirely sclerotized ventrally. Endophallic sclerite small, apodeme made of a thin anterior dorsal crest and narrow lateral lamellas. Female. FWs dorsal field with 8–9 strong longitudinal veins (m = 8, n = 10) and faint transverse ones. Subgenital plate not indented apically ( Fig. 9B ). Ovipositor longer than FIII, its apex rounded and smooth. Female genitalia: Copulatory papilla ( Fig. 11 C–D) thin and conical, widened basally; sclerotization strong basally and apically, its membrane plicate. Life history traits. X. marmoratus lives on low vegetation in bushes and grass in secondary habitats and along roads. The species has a nocturnal activity; males call at night from the vegetation. See Olivero & Robillard (2017) for description of peculiar mating behaviours. Calling song ( Figs 12B , 14 ). At 26.5°C, the calling song of X. marmoratus is made of relatively long syllables, each corresponding to one FW closure. Syllables form a two-part echeme: 1–3 singleton syllables (m = 2, n = 10), followed by a chirp made of three syllables, sometimes duplicated. The amplitude profile of the call shows that the singletons are usually less loud than the chirp. Total echeme duration is 711 ± 33 ms, for an echeme period of 6776 ± 368 ms (echeme duty cycle = 10.5%). The syllables have the following characteristics: 1 st syllable duration = 51.8 ± 1.5 ms (period = 318.3 ± 35.6 ms); 2 nd syllable duration = 50.3 ± 1 ms; chirp duration = 183.8 ± 1 ms; chirp syllable duration = 49.5 ± 1.9 ms (period = 68 ± 0.8 ms). The frequency spectrum shows a pure tone fundamental peak corresponding to the dominant frequency at ca. 5.9 ± 0.2 kHz, with a clear harmonic series, the third harmonic ( ca. 18 kHz) being almost as powerful as the fundamental peak. Measurements. See Table 6 . Taxonomic discussion. The types of De Haan, supposed to be in Leiden, were not found in RMNH in 2006 (TR, pers. obs.), with no record mentioning them as loaned (Rob De Vries, curator of the Orthopteran collection in RMNH, pers. com. 2006; confirmation by Luc Willemse, current curator of the Orthopteran collection in RMNH, pers. com. 2018). Specimens possibly belonging to the original type series were also searched for in other European museums, but could not be found. We thus designate a neotype from Japan that will serve as a reference for future systematic works. BL PronL PronW FWL FWW HWT FIIIL FIIIW Neotype male 19.4 2.9 4.1 15.5 6.7 3.5 15.3 2.8 Males (n=4) 18.6–22 2.5–3 3.9–4.8 15.5–17 6.4–6.7 3.1–4.3 14.2–15.8 2.6–3.4 (Male mean) (20.4) (2.9) (4.3) (16.5) (6.5) (3.4) (15.3) (3) Females (n=5) 18.8–20 2.1–3.1 3.1–4.3 11.5–15 2.8–4 1.2–6.3 11.8–16.3 2.2–3.2 (Female mean) (19.1) (2.7) (3.7) (13.4) (3.3) (3.4) (14.4) (2.7) TIIIL TIIIs TaIIIs OL Ias Ibs Oas Obs Ids Ods Ols Neotype male 11.1 9 11 14 16 0 4 5 - Males (n=4) 11.1–15.8 5–12 10–12 11–20 11–16 0–2 3–7 5–7 - (Male mean) (14.1) (9) (11) (16) (5) (1) (5) (5) - Females (n=5) 12.1–14.9 4–10 7–12 13–18 9–13 0–2 2–5 5–10 14.1–19 (Female mean) (13.3) (8) (9) (16) (11) (1) (3) (7) (16.6) Gorochov (1992) distinguished two subspecies, X. m. marmoratus ( Haan, 1844 ) and X. m. unipartitus ( Karny, 1915 ) . In his study, he considered Gryllus ( Phalangopsis ) marmoratus Haan, 1844 ( type from Japan ), as the nominal subspecies Xenogryllus marmoratus marmoratus , while he established the subspecies X. m. unipartitus based on the species Heterotrypus unipartitus Karny, 1915 , which was described from one female from Taiwan (Takao, examined on photo). The type of H. unipartitus clearly corresponds to a female of Xenogryllus , however, given the continuous variation observed across the wide distribution of X. marmoratus , and the limited information available based on female morphology, there is no reason to maintain these two subspecies. We thus synonymise the subspecies under X. marmoratus , and H. unipartitus becomes a junior synonym of X. marmoratus , as previously proposed by Chopard (1968) .