Oecanthus castaneus Felix & Bouwman & Odé & Ketelaar & Pham & Bailey 2025, sp. nov.

Oecanthus castaneus Felix & Bouwman sp. nov. Figs 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172 References for Socotra. Krauss 1907: 17, 27, 30 [partim; as Oecanthus indicus]; Uvarov (in Uvarov and Popov (1957)): 364–365 [partim; as Oecanthus chopardi]; Gorochov 1993: 92 [partim; as O. chopardi]; Wranik 2003: 316, plates 146, 149 [partim; as O. chopardi]; Chintauan-Marquier et al. 2016: 60, 70 [as O. chopardi]; De Campos et al. 2022: 6 [as O. chopardi]. Material examined. Holotype. YEMEN ● 1 ♂, on alcohol; Socotra, Aloove area, Aloove vill. env. Jatropha unicostata shrubland with Boswellia elongata trees; 221 m a. s. l.; 12°31.2'N, 54°07.4'E [12.5200°N, 54.1233°E]; 19–20 Jun 2012; J. Bezdĕk, J. Hájek, V. Hula, P. Kment, I. Malenovský, J. Niedobová & L. Purchart leg.; NMPC SpCZ 12 YE 024 A. Paratypes. YEMEN ● 1 ♂; Sokótra; Jan 1899; O. Simony leg.; NMW ● 1 ♀; Sokótra; Feb 1899; O. Simony leg.; NMW ● 1 ♂ [former paratype of Oecanthus chopardi Uvarov, 1957]; Socotra, Moabbadh plain [Maabad], east of Hadiboh; [12.6377°N, 54.1499°E]; 10–12 Feb 1953; G. Popov leg.; NHMUK 016032520 ● 1 ♂; Socotra, Qualansiyah [Qalansiyah]; [12.6888°N, 53.4877°E]; 25 Mar 1967; K. Guichard leg.; NHMUK 016032747 ● 1 ♀; same as for previous; NHMUK 016032489 ● 2 ♂; Socotra, Hadiboh Plain; 50 m a. s. l.; [12.6216°N, 54.0522°E]; 12 Apr 1967; K. Guichard leg.; NHMUK 016032577, NHMUK 016032824 ● 1 ♀; same as for previous NHMUK 016032601 ● 2 ♀; Socotra, Hadiboh Plain; 30 m a. s. l.; [12.6216°N, 54.0522°E]; 2 May 1967; K. Guichard leg.; NHMUK 016032587, NHMUK 016032767 ● 1 ♀; Socotra, Husaant [Haasan]; 12.5016°N, 54.1452°E]; 29 Nov 1999; W. Wranik leg.; NMPC ● 1 ♀; Socotra, Di Lisha [Di Hashus]; 12°31'48"N, 53°59'08"E [12.5300°N, 53.9855°E]; 4 Apr 2008; B. Massa leg.; BMPC ● 1 ♂; Socotra, Qalansiyah river (Shata) [Bi’r Haarso]; [12.6273°N, 53.6076°E]; 6 Apr 2008; B. Massa leg.; BMPC ● 2 ♂, 3 ♀; Socotra, Wadi Ayehv [Wadi Ayhaft]; 12°37'17"N, 53°56'16"E [12.6213°N, 53.9377°E]; 10 Apr 2008; B. Massa leg.; BMPC ● 1 ♂; Socotra, Wadi Ayhaft; 266 m a. s. l.; 12.6059°N, 53.9927°E; 22 Feb 2009; R. Felix, J. Bouwman & R. Ketelaar leg.; RFPC SpRF 09 YE 327 ● 1 ♀; same data as for previous RFPC SpRF 09 YE 322 ● 1 ♂; Socotra, Ridah [Begobig], Momi Plateau; 350 m a. s. l.; [12.5294°N, 54.2949°E]; 24 Feb 2009; R. Felix, J. Bouwman & R. Ketelaar leg.; RFPC SpRF 09 YE 324 ● 1 ♂; Socotra, Halmi beach; 12°21.324'N, 54°04.780'E [12.3554°N, 54.0796°E]; 16 Jun 2009; V. Hula leg.; NMPC ● 1 ♂; Socotra, Wadi Ayhaft; 266 m a. s. l.; 12.6059°N, 53.9927°E; 26 Oct 2010; R. Felix, J. Bouwman & R. Ketelaar leg.; RFPC SpRF 10 YE 018 ● 1 ♂; Socotra, Hadiboh; 23 m a. s. l.; 12.6453°N, 54.0128°E; 3 Nov 2010; R. Felix, J. Bouwman & R. Ketelaar leg.; Sound recording RecRF 10202–206; RFPC SpRF 10 YE 119 ● 1 ♀; Socotra, Wadi Ayhaft; 200 m a. s. l.; 12°36.5'N, 53°58.9'E; [12.6083°N, 53.9816°E]; 7–8 Nov 2010; J. Hájek leg.; NMPC ● 1; Socotra, Shahab area, Baa vill. env. [Ba’a]; [12.5413°N, 54.1730°E]; 9 Nov. 2010; J. Hájek leg.; NMPC ● 1 ♀; Socotra, Noged Plain, Sharet Halma vill., env.; 20 m a. s. l.; 12°21.9'N, 54°05.3'E; [12.3650°N, 54.0883°E]; 10–11 Nov 2010; J. Bezdĕk leg.; NMPC ● 1 ♂; Socotra, Delisha vill. env. Jatropha unicostata shrubland, at light; 36 m a. s. l.; 12°41.2'N, 54°07.7'E; [12.6866°N, 54.1283°E]; 8 Jun 2012; J. Bezdĕk, J. Hájek, V. Hula, P. Kment, I. Malenovský, J. Niedobová & L. Purchart leg.; NMPC SpCZ 12 YE 032 ● 1 ♀; same as for previous NMPC SpCZ 12 YE 031 ● 1 ♀; Socotra, Noged Plain, Abataro, border of dunes and succulent bush; 20 m a. s. l.; 12°22.1'N, 54°03.4'E [12.3683°N, 54.0566°E]; 12–13 Jun 2012; J. Bezdĕk, J. Hájek, V. Hula, P. Kment, I. Malenovský, J. Niedobová & L. Purchart leg.; NMPC SpCZ 12 YE 039 ● 2 ♂; Socotra, Aloove area, Aloove vill. env. Jatropha unicostata shrubland with Boswellia elongata trees; 221 m a. s. l.; 12°31.2'N, 54°07.4'E [12.5200°N, 54.1233°E]; 19–20 Jun 2012; J. Bezdĕk, J. Hájek, V. Hula, P. Kment, I. Malenovský, J. Niedobová & L. Purchart leg.; NMPC SpCZ 12 YE 024 B, C ● 1 ♀; same as for previous; NMPC SpCZ 12 YE 022 ● 1 ♂; Socotra, Wadi Matyaf (lower part), Noged; [20–30 m a. s. l.]; [12.4505°N, 54.3013°E]; 21 Jan 2014; A. Carapezza leg.; BMPC. Additional material. YEMEN ● 1 ♂; Socotra, Hadiboh; 16 m a. s. l.; 12.6488°N, 54.0129°E; 21 Feb 2009; R. Felix, J. Bouwman & R. Ketelaar leg.; RFPC SpRF 09 YE 323 [damaged; only genitalia available] ● 1 ♂; Socotra, Shuab; 8 m a. s. l.; 12.5779°N, 53.4002°E; 1 Mar 2009; R. Felix, J. Bouwman & R. Ketelaar leg.; RFPC SpRF 09 YE 326 [damaged]. Generic placement. Oecanthus castaneus Felix & Bouwman, sp. nov. (Figs 162, 163), as well as O. chopardi Uvarov, 1957 (Fig. 173), the other tree cricket existing in the Archipelago, belong to the above-mentioned suprageneric ranks, based on the following characteristics, amongst others: the lateral field of the tegmen forming a sharp angle with the dorsal field; ovipositor straight in lateral view; male tegmen with a large mirror with two dividing veins and an almost absent apical field; dorsal valves of the ovipositor bifurcated apically; pseudepiphallic sclerite wider than long, with two main lobes and long rami; arc projecting anteriorly, with two long distal prolongations; cerci longer than FII (De Campos et al. 2022). The two Socotran species have many characteristics that are considered diagnostic to Viphyus (Otte, 1988): a weakly prognathous head (Fig. 164 A); two thin dark lines bordering the light mid-line of the pronotum (Fig. 164 B), ventral apical spurs on both TI and TII (Fig. 164 E); black spots on the basal antennal segments (Fig. 164 A); spots on the outer surface of the hind femur (Figs 164 C, 165 A); two outer and three inner, dorsal, subapical spurs on TIII (Fig. 164 F); a well-developed metascutum and metascutellum, both more or less of the same length (Fig. 166); extensive dark markings on the tegmina (Toms and Otte 1988). See Cigliano et al. (2024 b) for photographs of Viphyus victorinoxi Otte, 1988, the type species of the genus. Viphyus, however, has a median scutal tubercle, missing in O. castaneus sp. nov. and O. chopardi (Fig. 166). Furthermore, in Viphyus, the main lobes of the pseudepiphallus in the phallic complex are steeply pointing upwards. In the Socotran species, the main lobes of the pseudepiphallus do not steeply slope upwards (Fig. 168 E, F). At the same time, the pseudepiphallic parameres in the Socotran species differ from those in Viphyus and resemble those of Oecanthus. In (most) Oecanthus, however, there are no ventral apical spurs on TI or TII, only the metascutum is elaborately modified, a median scutal tubercle is presen, and TIII generally has 4–5 pairs of subapical spurs instead of 2–3 (Chopard 1955; Walker and Gurney 1967; Toms and Otte 1988; Collins in litt 2024). Diagnostic notes. Oecanthus castaneus Felix & Bouwman, sp. nov. can be separated from O. chopardi by its distinctive warm appearance due to its orange-brown colours and extensive brown markings on the wings (Figs 162, 163). Oecanthus chopardi is never brownish, but always uniformly whitish to pale straw, often with bright greenish tones (Fig. 173). Where the sides of the head, pronotum and legs are orange-brown in O. castaneus sp. nov., they are whitish to pale straw in O. chopardi. Dorsally, the head and pronotum of O. castaneus sp. nov. are darker brown, whereas O. chopardi has greenish tones in those parts (Fig. 173). O. castaneus sp. nov. has almost entirely blackish-brown antennae, except for the lighter scape and pedicle, while in O. chopardi, the antennae are light and of the same colour as the body (Figs 173, 177). The tegmina of O. castaneus sp. nov. are extensively marked blackish-brown, but there is variation in the extent (Fig. 167 A). The base of the tegmina is variably dark brown and the file and the plectrum are flanked with intensive blackish markings (Fig. 167 A, C). There is a large brown spot in the chordal area, halfway to the inner edge of the tegmina. The veins in the distal part of the dorsal field are all bordered brown, the cells are marked with infumated spots and the wing’s apex is heavily infumated (Fig. 167 A). In O. chopardi, the tegmina are translucent white to greenish, with only two small dark markings, one on the distal part of the file bordering the plectrum and a smaller one in the chordal area (Fig. 167 B). The tegmina in male O. castaneus sp. nov. are slightly narrower and shorter than O. chopardi (Table 8; Fig. 167); in females, they are at least shorter (width not measured). The female cerci and ovipositor of O. castaneus sp. nov. are shorter (<4.0 mm and <4.5 mm, respectively) than in O. chopardi (> 4.5 mm and> 5.0 mm, respectively) (Table 8; Fig. 165). In O. castaneus sp. nov., both inner and outer ventral lobes of the hind knee are lined black dorsally (Fig. 165 A), whereas, in O. chopardi, they are only tipped black (Fig. 165 B). The female subgenital plate of O. castaneus sp. nov. is triangular with an obtuse apex; in O. chopardi, it is more trapezoid with a broadly rounded to truncated apex. The metanotum of both species does not differ markedly, which is a common phenomenon in closely-related species (Walker and Gurney 1967). The stridulatory file in O. castaneus sp. nov. is straight with 45–54 teeth (Fig. 167 C). The only studied specimen of O. chopardi has 59 teeth (Table 8) and a slightly more sinuous file (Fig. 167 D). The pseudepiphallic sclerite in O. castaneus sp. nov. forms a transverse, narrow bridge with a slightly curved anterior margin in the dorsal view (Fig. 168 A). In O. chopardi, the transverse bridge is broader and the anterior margin is almost straight in dorsal view (Fig. 168 B). The main lobes of the pseudepiphallus differ slightly between both species. In O. castaneus sp. nov., the two lobes point more directly caudal and are somewhat slender, while in O. chopardi, the lobes curve more inwards and are somewhat coarser with a broader base (Fig. 168). O. castaneus sp