Silvestrichilis shiyanensis Shen, Wang & Zhang, 2025

Silvestrichilis shiyanensis Shen, Wang & Zhang , sp. nov.

Chinese name: 十堰aDz

LSID: urn:lsid:zoobank.org:act:FC5DB6DD-9B8C-4835-BD4C-61E2B3B22EFB

Figures 1–11 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11

Type specimens and type locality. Male holotype, 4 female paratypes (in ethanol), Wudangshan Residential District , Danjiangkou, Shiyan City, Hubei Province, China , 32°30′N, 111°3′E, 10.III.2023, on stones from shrubby mountain areas ( Figs. 1B, C View FIGURE 1 ), coll. Ling-Yun Wang. All type specimens deposited in the Animal Herbarium, Zhejiang Normal University, Jinhua, China GoogleMaps .

Description. Whole body covered with dense, moss-like scales ( Fig. 1A View FIGURE 1 ); body colour brown to pale after scale removal; body length 7.86 mm in male and 9.72–10.76 mm in females ( Figs. 2A View FIGURE 2 , 3A View FIGURE 3 ).

Head generally brown to pale brown, dark hypodermal pigments present at antennal base, frons, clypeus and genae. Labrum and clypeus with slightly curved, colourless setae. Frons slightly convex. Vertex smooth, convex ( Figs. 2B View FIGURE 2 , 3B View FIGURE 3 ).

Compound eyes dark, approximately elliptical, width greater than length, with a length-to-width ratio of 0.75 to 0.83 ( Figs. 2C View FIGURE 2 , 3C View FIGURE 3 ). In proportion to the head, the male’s compound eyes larger than those of the female, but without obvious difference in the shape of the eyes between male and female. In all female samples, a pale ringlike band at the outer margins of the compound eyes ( Fig. 3C View FIGURE 3 ), absent in the male specimen ( Fig. 2C View FIGURE 2 ). Ratio of length of the compound eye contact line to that of compound eyes 0.41–0.44. Paired ocelli sublateral, long ovoid to rounded rectangular, directly adjacent to the eyes. Ocelli dark in male, with width/length ratio 3.00, white in female, width/length ratio 2.17–2.50 ( Fig. 2C View FIGURE 2 , 3C View FIGURE 3 ). Ratio of length of paired ocelli to that of compound eyes 0.20 in male, 0.26–0.30 in females. Ratio of distance between inner margins of paired ocelli to combined width of compound eyes 0.63 in male, 0.53–0.56 in females.

Antennae provided with dark brown scales, ratio of length of antennae to that of body (without median terminal filament and cerci) 1.43 in male ( Fig. 2D View FIGURE 2 ), 1.13–1.21 in female ( Fig. 3D View FIGURE 3 ). Scape with short setae, length of scape nearly 2 times its width ( Figs 2D View FIGURE 2 , 3D, E View FIGURE 3 ). Flagellum provided with fine setae, having 10–12 divisions, and with 11–14 annuli in distal chains ( Figs. 2D View FIGURE 2 , 3D, F View FIGURE 3 ).

Mandibles devoid of scales, with 4 distinctive incisor denticles on apex, and with longitudinal grooves at bases of denticles. Molar area keratinized, smooth, brown to dark brown. Base of mandibles with some dark pigment and some setae on lateral margins ( Figs. 4A, B View FIGURE 4 , 5A, B View FIGURE 5 ).

Maxilla yellow to pale, palpus bearing dense scales; apex of galea with many small cilia, ventrodistal area with dark hypodermal pigment, similar pigments on the lateral margin of the stipe. Apex of lacinia with a distinctive golden colour. In male, ventral surfaces of segment II–VII of maxillary palpus with long hair-like setae, and segment Ⅴ–VII with short straight setae; these setae nearly absent on the ventral surfaces of maxillary palpus in females. On dorsal surfaces, fine setae on segment IV–VII in both sexes, along with several transparent dentiform setae on three distal segments ( Figs. 4C View FIGURE 4 , 5F View FIGURE 5 ). Ratio of length of segment VII to segment VI 1.08–1.18.

Labium brown to pale, palpus with long hair-like setae on lateral margins, denser in male ( Figs. 4D View FIGURE 4 , 5E View FIGURE 5 ). Ultimate article of labial palpus oval-triangular, with a deeper colour, apex bearing 16–31 long fine sensorial cones; length to width ratio for ultimate article 0.58–0.76 ( Figs. 4E View FIGURE 4 , 5C View FIGURE 5 ).

Thorax structures with usual covering of dense scales, front lateral angle of pronotum extended anteriorly, reaching the middle of scape. Mesonotum convex, well developed ( Figs. 2A View FIGURE 2 , 3A View FIGURE 3 ).

sp. nov.

Forefemur slightly widened in both sexes, with a small oval sensory field composed of 13 sensilla on distal area of femur in male ( Fig. 6A View FIGURE 6 ), length to width ratio 0.64. Hind tarsus 1.21 times longer than fore tarsus, 1.35 times longer than middle tarsus in male ( Figs. 6B, D, F View FIGURE 6 ). Female hind tarsus 1.05 times longer than foretarsus and 1.17–1.19 times longer than middle tarsus ( Figs. 7B, D, F View FIGURE 7 ). Hind tibia 1.16 times longer than foretibia, 1.35 times longer than middle tibia in male ( Figs. 6A, C, E View FIGURE 6 ). Female hind tibia 1.04–1.13 times longer than foretibia, 1.27–1.39 times longer than middle tibia ( Figs. 7A, C, E View FIGURE 7 ). Ratio of length of hind tarsomere III to the total length of hind tarsus 0.35–0.47. Length to width ratio for parts of the legs given in Table 1. Middle and hind coxae with styli, length of styli subequal to half that of coxae ( Figs. 6C, E View FIGURE 6 , 7C, E View FIGURE 7 ). Lateral margins of coxae with long setae, dorsoproximal area with distinctive dark pigments in fore and middle coxae; similar markings in the same area on the hind legs, but less extensive ( Figs. 6A, C, E View FIGURE 6 , 7A, C, E View FIGURE 7 ). Styli with short setae ( Figs. 6C, E View FIGURE 6 , 7C, E View FIGURE 7 ). Ventral surface of trochanter with fine setae ( Figs. 6A, C, E View FIGURE 6 , 7A, C, E View FIGURE 7 ). Ventral surfaces of femora, tibiae and tarsus with elongate needle-shaped macrochaetae; short, strong macrochaetae present at least on ultimate and penultimate articles of tarsi ( Figs. 6B, D, F View FIGURE 6 , 7B, D, F View FIGURE 7 ). Numbers of elongated, needle-shaped and short, strong macrochaetae on the legs given in Table 2. Pretarsus with two well-developed transparent claws ( Figs. 6B, D, F View FIGURE 6 , 7B, D, F View FIGURE 7 ).

Urocoxites Ⅰ–VII with 1 +1 eversible vesicles ( Figs. 8A–G View FIGURE 8 , 9A–G View FIGURE 9 ). Posterior angles of urosternites of the abdomen given in Table 3. Length ratios of urosternites, urocoxites, and styli given in Table 4. Inner posterior lobes of female urocoxites VII caudally extended, beyond the apex of the vesicles in the contracted state ( Fig 9G View FIGURE 9 ).

Male genitalia with two pair of parameres, anterior paramere on urocoxite VIII ( Fig. 10A View FIGURE 10 ), posterior paramere and penis on urocoxite IX ( Fig. 10C View FIGURE 10 ). Both anterior and posterior parameres with short oblique setae on inner margins, 1+5-segmented ( Fig. 10B, D View FIGURE 10 ). Length ratio of anterior paramere and posterior paramere 0.70. Penis 1+1 segmented, apex flattened, with fine setae, reaching the base of the penultimate article of posterior paramere, length ratio of penis to posterior paramere 0.72. Length of the ultimate article of penis twice its width ( Fig. 10D View FIGURE 10 ).

Ovipositor slender, elongate, surpassing apex of styli on urocoxites IX, of primary type, without fossorial spines or fossorial claws ( Figs. 11A, C View FIGURE 11 ). Anterior and posterior gonapophyses with 60–61 and 60–65 articles, respectively, without hook-shaped chaetae ( Fig. 11B, D View FIGURE 11 ). More than one-half of the basal segments of ovipositor glabrous, remaining segments with long, erect setae. Distal spines of gonapophyses as long as four distal articles altogether.

Caudal filament provided with filiform scales, apex conic ( Figs. 8H View FIGURE 8 , 9H View FIGURE 9 ), 10.6 mm in female, with 126 articles; fractured in male, 8.49 mm, with 108 articles. Length of caudal filament subequal to that of body (without caudal filament or cerci). Cerci provided with filiform scales, 4.44–5.20 mm, with 58–61 articles. Ratio of length of cerci to that of caudal filament 0.49.

Etymology. This new species is named after the collection locality, Shiyan City, China.

Phylogenetic relationships based on COX1 gene. Bayesian Inference (BI) analysis showed that Silvestrichilis shiyanensis sp. nov. represents an independent clade ( Fig. 12 View FIGURE 12 ). In the BI phylogenetic tree, S. shiyanensis sp. nov. is a sister clade of Dilta species.