Goniocotes cacumentalis Gustafsson, Tian, Ren, Li, Sun & Zou, 2024, sp. nov.

Goniocotes cacumentalis sp. nov. urn:lsid:zoobank.org:act: 8669F58C-2D3B-4DC6-A9E1-B27B9CDCA28D Figs 6–10 Diagnosis The following combination of characters makes G. cacumentalis sp. nov. unique among all known species of Goniocotes: marginal carina very narrow (Fig. 8); os macroseta in both male and female (Figs 6–7); male tergopleurites II–III with 3–4 tps mesosetae on each side (Fig. 6); female tergopleurites II–IV with psps macrosetae (Fig. 7); smns present (Figs 6–7); female with>20 vms microsetae on each side of vulval margin (Fig. 10); mts4–5 both situated on occipital bulge (Fig. 8; this is more clear in the male where the bulge is more prominent). Two of these characters are especially important, and are to our knowledge unique within Goniocotes: the female os being macrosetae, and the mts4 being situated on the occipital bulge, and much closer to mts5 than to mts3. In all other species of the genus we have examined (either as specimens or from illustrations and drawings), female os are microsetae. As such, G. cacumentalis sp. nov. may have some of the best characters to separate females of all known species in Goniocotes. The placement of mts4 close to mts3 on a relatively flat part of the posterior head margin, and mts5 apically on the occipital bulge is constant throughout most of the Goniodidae, including all other Goniocotes. However, in the Goniodes from peacocks (Pavo Linnaeus, 1758), both mts4–5 are on the occipital bulge, and Kéler (1940) illustrated the female of G. gregarius with mts5 on the median margin of the occipital bulge, not apically. This character is thus variable within the family, and requires further study. The presence of psps on female tergopleurites II–V is also rare in Goniocotes, and otherwise only known from G. diplogonus, G. kristinae, and G. sarissa sp. nov. There are no other characters that suggest any close relationship between G. cacumentalis sp. nov. and these species. Etymology The specific epithet is constructed from ‘ cacumen ’, Latin for ‘peak’ or ‘summit’. This refers to the high altitudinal range of the host and its louse, which extends to almost 6000 m (Madge & McGowan 2002), the highest by far of all known Goniocotes. To this is arbitrarily added the ending ‘- talis ’. Type material Holotype (ex Tetraogallus tibetanus) CHINA • ♂; Tibet; 1877; collector unknown; Brit. Mus. 1974-240, NHMUK010676049; NHML [male closest to the female on the slide, marked with a black dot]. Paratypes (ex Tetraogallus tibetanus) CHINA • 1 ♂, 1 ♀; same data as for holotype; NHML. (ex Tetraogallus tibetanus aquilonifer) INDIA • 1 ♂, 10 ♀♀; Sikkim; date unknown; R. Meinertzhagen leg.; 13400, NHMUK010676048; NHML • 2 ♀♀; Ladakh; Jun. 1925; R. Meinertzhagen leg.; 248, NHMUK010676047; NHML. Type host Tetraogallus tibetanus Gould, 1854 – Tibetan snowcock. Type locality Tibet, China. Other host Tetraogallus tibetanus aquilonifer Meinertzhagen & Meinertzhagen, 1926. Description Frons broadly rounded (Fig. 8). Marginal carina very narrow, attendant canals not clear. No internal line. Preantennal nodi narrowed basally and expanded medianly, but shape differs among specimens. Male os macrosetae; mts4–5 both situated on occipital bulge, which is slight. Lateral temporal margins convex, divergent. Occipital nodi slender. Thoracic and abdominal segments and chaetotaxy as in Figs 6–7. Rhombic sclerite fused to pronotum. Pronotum with rounded postero-lateral corners. Proepimera not fused medianly. Postero-lateral corner of pteronotum not extended laterally; posterior margin gently rounded; single smns present. Male tergopleurites reduced on more posterior segments, but tergopleurites II–VIII are extended medianly to reach near site of ss; lateral tergopleurite IX+X slender, curved, reaching median sclerite IX+X, with which it may overlap slightly. Lateral accessory sternal plates absent. Male abdominal chaetotaxy: ss present on tergopleurites II–VIII; tps present on tergopleurites II–V, numbers decreasing on more posterior segments; psps present on tergopleurites II–VII; aps absent; ps present on segments III–VIII. Female abdominal chaetotaxy: ss present on tergopleurites II–VIII; tps and aps absent; psps present on tergopleurites II–VII; ps present on segments III–VIII. Male genitalia as in Fig. 9; solenoid, with no clear distal margin; pst not visible. Female genitalia as in Fig. 10; subgenital plate absent. Vulval margin flattened medianly, with 21–28 short, slender vms and 3–4 longer, thorn-like vss on each side; 5–7 (one specimen with 1–0) short, slender vos on each side. Subvulval plates absent. Measurements as in Table 1. Remarks Goniocotes cacumentalis sp. nov. is the first species in the genus to be described from a truly highelevation host, which typically is found at an altitude of 5000–6000 meters (Madge & McGowan 2002). Almost all other known species of Goniocotes parasitizing hosts that occur at altitudes> 4000 m (Table 3) are here transferred to the genus Dictyocotes. This suggests that species of Goniocotes s. lat. may be found in many more host species, including those of boreal and alpine environments, and that the lack of records from such hosts may be more an effect of the difficulty of sampling than an actual absence.