Citharognathus hosei Pocock, 1895

Citharognathus hosei Pocock, 1895 View in CoL

( Figs 9–12 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 , 13B View FIGURE 13 , 16A–B View FIGURE 16 )

Citharognathus hosei Pocock 1895: 183 View in CoL , pl. 10, fig. 1 (female).

Additional description to female (SMNS-Aran-003987), with body length: 49 (including chelicerae).

Color (in life) ( Fig. 12A View FIGURE 12 ): The basic coloration of the legs is silver-grey with long reddish hairs and the joint rings between the leg segments are all clearly visible and white. Carapace and chelicerae are light gray. Opisthosoma is brown with a clearly visible stripe pattern.

Carapace ( Fig. 9A View FIGURE 9 ): length 18.0, width 14.5. Fovea low, cephalic region slightly higher than thorax, longer than wide, surface covered with short setae. Fovea: 2.87 wide, 2.95 curved length, procurved, deep, one third narrower than OT.

Chelicerae ( Fig. 9F View FIGURE 9 ): length 10.0, width 8.0. Strong, reddish setal fringe along promargin. Retrolaterally with a large field of plumose setae, basal with a field of strong plumose setae, baso-ventrally with 5 long, sword-shaped plumose setae.

Clypeus: width 0.24, clearly smaller than width of OT.

Eyes: OT length 2.57, width 3.79. Anterior row straight, posterior row slightly procuved. Diameter ALE: 0.81; AME: 0.94; PLE: 0.65, PME: 0.56; inter distances: ALE – AME: 0.32; ALE – PLE: 0.25; PLE – PME: 0.10; PME – AME: 0.17; AME – AME: 0.44; MOQ anterior wider than posterior.

Maxillae ( Fig. 9E View FIGURE 9 ): length (incl. trochanter) 10.55. Prolaterally plano-convex, anterior prolateral lobe well pronounced. Retrolateral face mostly glabrous. Prolateral face with 11 thorn-like black spines pointing forward and increasing in length and size from posterior to anterior and dorsal to ventral, in two rows, some fine plumose setae above suture intermixed with several strong spiniform setae, dorso-anterior edge with a row of 4 elongated black spiniform setae.

Labium: length 1.96, width 2.63, 105 cuspules on anterior area of labium.

Sternum ( Fig. 9B View FIGURE 9 ): length 9.69, width 7.07. Wider posteriorly than anteriorly, with a thin intermix of short setae and sparse longer setae, more so along edges. No spines on edges, but thicker setae along opposing edges of coxa IV. Sternal sigilla: three pairs (not including labio-sternal sigilla), glabrous, PSS largest, ovoid, length 1.21, 1.10 from sternum edge, 2.29 between PSS, PSS and MSS clearly visible. Anterior pair obscured by setae, middle pair smaller than PSS and anterior pair smaller than middle pair. Labiosternal groove: glabrous, slightly narrower medially, groove with low oblong cuticular mound on either side of medial narrowing.

Leg setation: All segments distodorsally with short blunt setae. Retrolateral surface of tib. and met. IV with distinct thick pencillate setal fringe, less noticeable on pat., absent on fem.; numerous short stout spiniform setae on patellae, tibiae and metatarsi of leg III and IV ( Figs 9C View FIGURE 9 , 12A View FIGURE 12 , 13B View FIGURE 13 ).

Legs: formula IV, I, II, III (compared from Holotype). LRF ~ 91 (from Holotype, in existing specimen, both leg I are missing). Leg lengths (fem., pat., tib., met., tar., total): palp 9.0, 4.5, 6.0, –, 6.5, 26. I missing. II 11.5 , 6.0, 8.5, 7.5, 7.0, 40.5. III 10 , 6.0, 6.5, 7.0, 5.5, 35. IV 12.5 , 6.0, 10, 9.0, 6.5, 44. Tar. IV uniform without transverse pallid medial suture .

Scopula: met. and tar. II – IV, undivided. Met. I: missing; II: 80%; III: 75%; IV: 60%.

Coxae: coxae I – IV covered ventrally with fine setae, intermixed with longer darker setae, apically, darker basally. Both leg I missing, IV widest, not as rectangular as III. Prolateral margins of II–IV, retrolateral margins of I–IV and apical ventral margins of I–IV, increasing from anterior to posterior, with longer setae, absent along prolateral margin of I. Ventral measurements for coxae: length–palp 26. Ventral measurements for coxa + trochantera: length; I–missing; II–9.0; III–7.5; IV–8.5. Fine plumose setae on prolateral face, intermixed with numerous elongated black spiniform setae.

Spines: Palp Tib.: 4 v, a, pl; 8 v, a, rl; Leg: I missing; III Pat.: 3 v, a, pl; 1 v, a, rl; Tib.: comb of spines a, v, rl + pl; Met.: 2 d, a, rl; IV Tib.: comb of spines a, v, rl + pl; Met.: 2 d, a, rl; 2 d, a, pl.

Claws: no third claw on leg IV.

Abdomen: length 21, wide: 12.

Genitalia ( Fig. 9D View FIGURE 9 ): Spermatheca undivided and consisting of two lobes connected by a deep dent in the middle. Width 3.10, height at the highest point of the left lobe 1.08, of the right lobe 1.14, at the lowest point in the middle 0.22. The angle between the two lobes is 81.05°.

Spinnerets: PMS: length 2.51; PLS: length 6.33.

Description of Male (SMNS, Aran-003502), with body length: 30.96

Color (in life) ( Fig. 12B View FIGURE 12 ): The overall coloration is fawn brown with longer pale brown setae, darker ventrally. The femora, carapace and chelicerae have a slight intermix of pale pink pubescence. Opisthosoma is brown without any pattern.

Carapace ( Fig. 10A View FIGURE 10 ): length 11.9, width 10.2. Fovea low, cephalic region higher than thorax, longer than wide, surface covered with short setae. Fovea: 1.0 wide, slightly recurved, deep, almost twice the width of OT.

Chelicerae ( Fig. 10F View FIGURE 10 ): length 7.0, width 4.4. strong, reddish setal fringe along promargin.

Clypeus: width 0.18, smaller than width of OT.

Eyes: OT length 2.04, width 2.94. Anterior row straight, posterior row slightly procuved. Diameter ALE: 0.62; AME: 0.85; PLE: 0.57, PME: 0.35; inter distances: ALE – AME: 0.25; ALE – PLE: 0.23; PLE – PME: 0.09; PME – AME: 0.13; AME – AME: 0.20.

Maxillae ( Fig. 10E View FIGURE 10 ): length (incl. trochanter): 6.97. Prolaterally plano-convex, anterior prolateral lobe well pronounced. Retrolateral face mostly glabrous. Prolateral face with 11 thorn-like black spines pointing forward and increasing in length and size from posterior to anterior and dorsal to ventral, in two rows. Some fine plumose setae above suture intermixed with strong spiniform setae, dorso-anterior edge with a row of 6 elongated black spiniform setae.

Labium: length 1.35, width 1.86, wider posteriorly, 85 cuspules in anterior area of labium surface.

Sternum ( Fig. 10B View FIGURE 10 ): length 6.35, width 4.85. Wider posteriorly than anteriorly, with a thin intermix of short setae and sparse longer setae, more so along edges. No spines on edges, but thicker setae along opposing edges of coxa IV. Sternal sigilla: three pairs (not including labio-sternal sigilla), glabrous, PSS largest, ovoid, length 0.62, 0.42 from sternum edge, 2.28 between PSS and clearly visible. Middle and anterior pair obscured by setae, middle pair smaller than PSS and anterior pair smaller than middle pair. Labiosternal groove: glabrous, slightly narrower medially, groove with low oblong cuticular mound on either side of medial narrowing.

Leg setation: All segments distodorsally with short blunt setae. Retrolateral surface of leg IV only with longer hairs.

Legs: formula I, IV, II, III. LRF~ 106. Leg lengths (fem., pat., tib., met., tar., total): palp 8.5, 5.0, 7.5, –, 5.5, 26.5. I 15.5, 8.0, 14, 12, 6.5, 56. II 12, 7.0, 10, 11, 7.0, 47. III 11, 5.0, 9.0, 10, 7.0, 42. IV 15.5, 5.5, 13.5, 12, 6.5, 53. Tar. IV uniform without transverse pallid medial suture. Tibial apophysis on leg I ventral with a single prolateral apophysis with numerous spines at its tip.

Scopula: met. I – IV undivided, tar. I–III undivided, tar. IV parted. Met. I: 82%; II: 79%; III: 72%; IV: 54%.

Coxae: coxae I–IV. Ventral measurements for coxa + trochanter length; Palp: 7.24; I–9.60; II–8.35; III–7,29; IV–8.25.

Spines: Leg: I Tib. 1 v, a, rl; II Tib. 1 v, a, rl; Met. 1 v, a, m; 1 v, a, rl; III Tib. 2 v, a, rl; Met. 1 d, a, pl; 1 d, a, rl; 1 v, a, rl; 1 v, a, m; 1 v, a, pl; IV Tib. 1 v, a, pl.; Met. 1 v, a, pl; 1 v, a, m; 1 v, a, rl.

Claws: all unarmed, no third claw on leg IV.

Abdomen: length 12.06, wide: 7.37

Palpal bulb ( Fig. 11A–F View FIGURE 11 ): Embolus with two keels, PS and A, tegulum ventrally basal without a bulge-like process (VTM), ERF~ 40.

Spinnerets: PMS: length 1.11; PLS: length 5.89.

Distribution. Malaysia ( Sarawak).

Natural history. Two populations of C. hosei are known today, both in Sarawak (Borneo). One population is in Bukit Lambir National Park and the nearby area, where they are live sympatrically with Phormingochilus everetti Pocock, 1885 and the other known population is around Long Akah, where they coexist with Phormingochilus pennellhewlettorum Smith & Jacobi, 2015 . These spiders live in dipterocarp forests and can typically be found in tree trunk or branch cavities ( Fig. 16A–B View FIGURE 16 ) that are strategically sheltered from direct rainfall. This positioning helps prevent excess water from accumulating inside the holes, which could otherwise create unsuitable living conditions. In September, mature males can be found wandering and searching for females. Oviposition is believed to take place around February to April, as one egg sac from which spiderlings had hatched just recently had been found in May (Rossez & Ménart 2024, pers. com.).