Damarchus dao, Schwendinger & Hongpadharakiree, 2023

Schwendinger, Peter J. & Hongpadharakiree, Komsan, 2023, Three new and exceptional Damarchus species from Thailand (Araneae: Bemmeridae), Zootaxa 5336 (4), pp. 481-508 : 496-500

Damarchus dao sp. nov.

Figures 5D , 11–13

Holotype. MHNG-ARTO-0034015; male (matured 29.IX.1990); Thailand, Chiang Mai Province, Chiang Dao District, Doi Chiang Dao , 19°24’47”N, 98°54’46”E, 560 m; 22.IX.1990; leg. P.J. Schwendinger.

Paratypes. MHNG-ARTO-0034016-0034017; 2 females (allotype MHNG-ARTO-0034016); same data as for holotype. MHNG-ARTO-0034018; 1 female; from the type locality; 6.III.1987; leg. P.J. Schwendinger. THNHM; 1 female; from the type locality; 6.III.1987; leg. P.J. Schwendinger.

Etymology. The epithet refers to the type locality, Doi Chiang Dao, and to the speckled dorsal side of the opisthosoma of this species. “Dao” (spoken with a long “a”) is the Thai word for “star”.

Diagnosis. Different from all other described Damarchus species by males having three megaspines on their tibia I coupling spur ( Fig. 11G, I–J ). Female genitalia different from those of all other known Bemmeridae by spermathecae having 1–3 receptacles ( Fig. 13 ). Both sexes with leg I darker than palp and legs II–IV; opisthosoma dorsally speckled with numerous light spots ( Figs 11D , 12E ).

Description of male holotype. Colour in alcohol: Carapace orange-brown, pars cephalica slightly darker than pars thoracica, with dark patches lateral of eye mound; eye mound black except for orange-brown posterior area between PME ( Fig. 11A ). Ventral side of prosoma light brown; coxae of legs and palps slightly greyish ( Fig. 11B ). Chelicerae light brown; claws very dark brown. Palps with trochanter and femur light brown; patella and tibia light yellow-brown; tarsus reddish brown ( Fig. 11K–M ). Legs mostly light brown, dorsally slightly darker than ventrally; leg I slightly darker than legs II–IV. Opisthosoma dorsally dark grey-brown, with numerous small light spots in posterior two-thirds ( Fig. 11D ); ventral side light brown, mottled with dark; spinnerets and anal tubercle cream-coloured; genital area very light brown ( Fig. 11E ).

Morphology and measurements: Body 11.14 long. Carapace 5.19 long, 4.25 wide, its anterior margin slightly recurved, its posterior margin invaginated ( Fig. 11A ); pars cephalica low, not arched, as in male of D. pylorus sp. nov.; few short grey hairs on pars cephalica and on coxal elevations of pars thoracica; long strong bristles on lateral and posterior carapace margins and in front of and behind eye mound; no hairs close to fovea. Fovea widely Ushaped, 0.57 wide, occupying 14% of carapace width at that level ( Fig. 11A ). Eight eyes on low but distinct mound; eye group 0.52 long, anterior eye row essentially straight, 1.12 wide, posterior eye row slightly recurved, 1.13 wide. MOQ 0.49 long, 0.61 wide anteriorly, 0.74 posteriorly. Eye diameters: AME 0.30, ALE 0.35, PME 0.19, PLE 0.25. Proximal article of chelicera 1.17 long, without intercheliceral tumescence; ventral groove with 8/8 teeth arranged in a medially transposed row (as in D. pylorus sp. nov., see Fig. 3I ) on promargin and a short row of several tiny light-coloured medioproximal denticles; rastellum sessile, composed of six quite long and weak spines in a single row above fang articulation. Palpal coxa 1.75 long, 0.97 wide; anterior lobe short, without serrula; with about 40 relatively long, peg-like cuspules in prolateral-proximal corner. Labium 0.42 long, 0.94 wide, with two peg-like cuspules ( Fig. 11C ). Sternum 2.79 long, 2.21 wide; labiosternal suture quite long and deep, fused with anterior pair of sigilla; three pairs of free sigilla, anterior and median pair small and close to sternal margin, posterior sigilla ellipsoid, about two times as long as wide, more remote from margin, medially separated from each other by almost twice their length ( Fig. 11B ).

Palp ( Fig. 11K–M ) 6.29 long (2.27 + 1.23 + 1.95 + 0.84). Tibia with a weak prolateral-median spine and several long strong ventral bristles, otherwise without modifications. Tarsus short, without spines, strong bristles or scopula. Trichobothria: 7+ 6 in two rows on tibia, 9/ 10 in a zig-zag row on tarsus. Palpal organ quite typical for the genus: proximal part bulbous, large and wide; embolus long and narrow, gradually tapering, its apex very thin and slightly curved; no laminae or ribs on lower side, no para-embolic apophysis.

Legs 3214; femora I–II slightly more compressed than femora III–IV. Leg I 18.06 long (4.94 + 2.53 + 4.29 + 3.90 + 2.40); leg II 16.57 long (4.55 + 2.34 + 3.77 + 3.70 + 2.21); leg III 13.30 long (3.57 + 1.88 + 2.53 + 3.47 + 1.85); leg IV 18.84 long (5.13 + 2.18 + 4.45 + 5.13 + 1.95). All patellae shorter than corresponding metatarsi. Leg tarsi not pseudosegmented and without spines; tarsi I–II slightly spindle-shaped, tarsi III–IV cylindrical. Scopulae covering entire ventral side of tarsi I–II, absent from tarsi III–IV. Metatarsal preening combs absent from legs I–II, expressed as dense proventral and retroventral groups of 3–4 long thin bristles on legs III–IV. Leg I: Metatarsus slightly bent at base, with a large, elongate median group of spinules proventrally ( Fig. 11G–H ); tibia cylindrical, not incrassate but thicker than metatarsus I, having a strong proventral coupling spur; the latter distally slightly wider than proximally, distinctly set back from tip of tibia and standing off from its axis at about 45°, tipped by three long, claw-like megaspines, the laterals more strongly curved than the median one ( Fig. 11G, I–J ).

Spines: Leg I: patella v1; tibia p2, v6 (including 3 megaspines on coupling spur); metatarsus p1, v3. Leg II: patella v1; tibia p1, v4; metatarsus p1, v3. Leg III: patella p3; tibia p1/2, d0/1, r2, v4; metatarsus p2/3, d5, v3. Leg IV: patella, 0; tibia r2, v2; metatarsus p2, d3, v5. Trichobothria: 7–10 each in two rows on tibiae, 10–20 in a single irregular row on metatarsi, 9–15 in a single zig-zag row on tarsi. Paired tarsal claws with 10–12 teeth in an S-shaped row on anterior legs, 7–9 on posterior legs; unpaired claw indiscernible on all legs.

Opisthosoma oval, 4.58 long, 3.12 wide; densely covered with long strong bristles and short weak hairs on dorsal side ( Fig. 11D ), and with medium-long and medium-strong bristles on ventral side ( Fig. 11E ). PMS 0.45 long, separated from each other by 0.19 (about their width); PLS 3.04 long (proximal article 0.84, median article 0.42, distal article 0.71), separated from each other by 0.68 (1.5 times width of proximal article; Fig. 11E–F ).

Description of female allotype. Colour in alcohol:As in male, except for the following. Carapace and chelicerae more reddish. Areas lateral of eye mound lighter instead of darker (in male) than other parts of carapace ( Fig. 12A cf. Fig. 11A ). Distal part of chelicerae distinctly darker than proximal part; cheliceral fang almost black. Leg I much darker than other legs and palps. Palpal patella and tibia cream-coloured, distinctly lighter than other palpal articles ( Fig. 12G ). Palpal tarsus (especially distal two-thirds) distinctly darker than in male ( Fig. 12G cf. Fig. 11K–M ); palpal coxae and labium slightly darker than in male ( Fig. 12C cf. Fig. 11B ).

Morphology and measurements: Body 18.12 long. Carapace 6.49 long, 5.13 wide, its anterior margin slightly recurved, its posterior margin slightly and widely invaginated ( Fig. 12A ); pars cephalica in profile more strongly arched than in male, with a distinct elongate and bent lateral depression on each side at transition between pars cephalica and pars thoracica ( Fig. 12B ); pars cephalica with more hairs than in male, covering whole area between eye mound and fovea; hairs in median row behind eye mound distinctly longer and stronger than in male, spiniform bristles on lateral margins of carapace distinctly weaker ( Fig. 12A cf. Fig. 11A ). Fovea widely U-shaped, 0.75 wide, occupying 15% of carapace width at that point. Eye mound low, at anterior margin of carapace; eye group 0.64 long, anterior eye row essentially straight, 1.46 wide, posterior eye row slightly recurved, 1.44 wide. MOQ 0.61 long, 0.75 wide anteriorly, 1.02 posteriorly. Eye diameters: AME 0.38, ALE 0.35, PME 0.27, PLE 0.23. Proximal article of chelicera 2.73 long, stronger than in male, without intercheliceral tumescence; ventral groove with 8/9 teeth arranged in a medially transposed row on promargin and with a short field of 9/13 tiny black medioproximal denticles; rastellum sessile, composed of about 20–30 distinctly pointed and relatively long spines in several rows plus several similarly thick but more strongly pointed spines above fang articulation. Palpal coxa 2.66 long, 1.56 wide; no serrula; with about 60–70 short domed cuspules in prolateral-proximal corner. Labium 0.71 long, 1.36 wide, with three short, domed cuspules ( Fig. 12D ). Sternum 3.51 long, 2.95 wide; posterior sigilla elongate, medially separated from each other by their length ( Fig. 12C ).

Palp 9.41 long (3.12 + 1.75 + 2.14 + 2.40). Trichobothria: 6/7+6/ 7 in two rows on tibia, 12 in an irregular row on tarsus. Spines: patella p2, tibia p7/8, v5, tarsus v1. Tibia dorsally with an indistinct subdistal pseudosegmentation ( Fig. 12G ). Tarsus with scopula covering almost entire length of article prolaterally and proventrally, but only its distal two-thirds retrolaterally and retroventrally; palpal claw with seven teeth in proventral row.

Legs 3214; leg I without modifications. Leg I 16.55 long (4.64 + 2.95 + 3.60 + 3.15 + 2.21); leg II 14.67 long (4.09 + 2.76 + 2.95 + 2.86 + 2.01); leg III 11.46 long (3.31 + 2.21 + 1.79 + 2.53 + 1.62); leg IV 16.79 long (4.81 + 2.76 + 3.54 + 3.93 + 1.75). All patellae shorter than corresponding metatarsi (in contrast to females of D. pylorus sp. nov. and D. lanna sp. nov.). Scopulae rather thin, covering entire ventral side of tarsi I–II, plus distal five-sixth of metatarsus I and distal fifth of metatarsus II only proventrally (very thin); no scopulae on legs III–IV. Metatarsal preening combs absent on leg I; on metatarsus II a proventral comb composed of 2/4 bristles; on metatarsus III a proventral comb of 5/5 and a retroventral comb of 4/4 bristles; on metatarsus IV a proventral comb of 3/3 and a retroventral comb of 3/4 bristles.

Spines: Leg I: patella p1 (indistinct on right leg); tibia p3, v5/6; metatarsus p1, v5. Leg II: patella p2; tibia p3, v5/6; metatarsus p1, v4/5. Leg III: patella p3; tibia d1, p2, r1/2, v5 (weak); metatarsus d7/8, v4/5. Leg IV: patella, 0; tibia r2, v6/7 (weak); metatarsus d3, p0/1, v6. Dense patches of rather weak (in comparison to D. lanna sp. nov.) spinules dorsally on patella III and patella IV (on the latter article spinules becoming thinner in distal half), divided by an oblique glabrous band, plus a dorsodistal group of rather strong spinules on femur IV. Trichobothria: 7–8+ 8–9 in two rows on tibiae, 9–14 in a single irregular row on metatarsi I–III and 20 on metatarsus IV, 10–14 in a zig-zag row on tarsi. Paired tarsal claws with 7–9+12–14 teeth in two rows (in exterior row more numerous than in interior row) on legs I–II, 3–4+4–5 on legs III–IV; unpaired claw bare and well developed on all legs ( Fig. 12H ).

Opisthosoma oval ( Fig. 12E–F ), 8.80 long, 6.23 wide; hair cover lacking long bristles (present in male). PMS 0.84 long, separated by 0.42 (slightly less than their diameter); PLS 3.02 long (proximal article 1.33, median article 0.68, distal article 1.01), separated by 0.97 (distinctly more than diameter of proximal article) ( Fig. 12F ).

Vulva ( Fig. 13A ): Genital atrium short and wide, anteriorly continuing into a widely separated pair of large, diverging spermathecae; these posteriorly wide, anteriorly narrowing, densely perforated by gland pores almost all over their entire surface. Right spermatheca (on left side in Fig. 13A ) running into a single (primary) receptacle with a semiglobular head facing laterad; proximal part of receptacular head less densely perforated with gland pores than distal part. Left spermatheca with same kind of laterad-facing primary receptacle in addition to a subdistal, anteriad-facing secondary receptacle with a small and weakly developed head (narrower than corresponding stalk) with only few gland pores.

Variation. Carapace lengths in females (n = 4) range 5.84–6.49; carapace widths 4.38–5.19. In all females examined the areas lateral of the eye mound are more or less distinctly lighter than other parts of the carapace ( Fig. 12A ). In one paratype the difference is rather indistinct; in another paratype the light lateral areas are connected to a light median area behind the eye mound. Three of the females examined (including the allotype) have three cuspules on the labium, one female has four labial cuspules. For variation in the shape of four vulvae see Fig.13 . All spermathecae terminate in a well-developed, laterad- or distolaterad-directed primary receptacle with a large, somewhat semiglobular head. All spermathecae but the right spermatheca of the allotype (seen on the left side in Fig. 13A ) additionally have 1–2 secondary receptacles.All secondary receptacles are smaller than the corresponding primary receptacle and have either no or only a weakly developed head.

Distribution. This species is only known from its type locality at the foot of Doi (= Mount) Chiang Dao in northern Thailand.

Relationships. Damarchus dao sp. nov. is clearly not closely related to D. pylorus sp. nov. and D. lanna sp. nov. The presence of more than one megaspine on the tibia I coupling spur , of an elongate proventral field of spinules on metatarsus I and of an unmodified palpal organ in the male indicate a much closer relationship to D. bifidus from India (see Gravely 1935: fig. 1a; Zonstein & Marusik 2014: fig. 25) and to similar congeners in SEAsia. The vulva of D. dao sp. nov. is basically of the common type, but its multiple receptacles are unique among the described Bemmeridae (see also Discussion). The closest relative of D. dao sp. nov. will presumably be found among the many yet undescribed Damarchus species in SE-Asia.

Biology. Habitat: This species occurs in a dry evergreen forest, a habitat that today is quite rare in the lowlands of seasonally dry northern Thailand. The humid biotope is sustained by rain water that disappears into subterranean aquifers in high altitudes and resurfaces in numerous streams at the foot of the limestone massif. The 2175 m high Doi Luang Chiang Dao (slightly higher altitudes are also given in the literature) is the third-highest peak in Thailand.

Burrow: The burrow structure is rather unusual for the genus Damarchus in that the side shaft does not branch from the main shaft at an angle but is a rectilinear extension of it ( Fig. 5D ). In five burrows excavated and measured the main shaft is 6.5–8.5 cm long and the side shaft 4.0– 4.5 cm, giving a total length of 10.5–13 cm. Three of the burrow entrances were level with the ground, two were raised on a rigid collar of silk and soil particles for 1.5 and 2 cm, respectively.

Phenology: The male holotype became adult a week after being collected at the end of September. In the field and in captivity, it plugged the area behind the mouth of the side shaft with soil particles. This was not observed in moulting females and appears to be only performed by males in preparation for their final moult, although this needs to be confirmed by further observations. After its final moult, the mature male continued feeding on woodlice and grasshoppers. A gravid female (with eggs visible through the cuticle of the opisthosoma) was collected in the field at the beginning of November. It laid eggs in captivity in Chiang Mai two months later. Two other females (collected in late September and then already mated) laid eggs in captivity at the end of December and in January , respectively. Two further females were found with egg sacs in their burrows in early March. These contained second instar spiderlings which moulted to the third instar, left the maternal burrow and build their own burrows at the end of March. Egg sacs were 1.2–1.3 cm long, 0.8–1.0 cm wide and 0.5–0.8 cm high. They were laterally suspended with silken bands in the side shaft of the maternal burrow ( Fig. 5D ), and contained 38– 75 eggs or spiderlings .

Figures

FIGURE 3. Damarchus pylorus sp. nov., female paratype (A, F, K, M), female allotype (B–E, G–J, L, N–P). (A–B) Habitus, dorsal view. (C) Carapace, lateral view. (D) Prosoma, dorsal view. (E) Same, ventral view. (F) Genital region, ventral view. (G) Spinnerets, ventral view. (H) Same, lateral view. (I) Groove of left chelicera, ventral view. (J) Tibia and tarsus of left palp, dorsal view; arrow indicating distinct pseudosegmentation. (K) Tip of right tarsus III, prolateral view; arrow indicating tiny unpaired claw (absent in other females). (L) Tip of left tarsus IV, prolateral view; arrow indicating distinct unpaired claw. (M) Tarsus and distal part of metatarsus of right leg IV, retrolateral view; short arrow indicating unpaired tarsal claw, long arrow indicating metatarsal preening comb. (N) Distal part of right metatarsus II, proventral view; arrow indicating metatarsal preening comb. (O) Distal part of left metatarsus IV, proventral view; arrow indicating metatarsal preening comb. (P) Same, retroventral view; arrow indicating metatarsal preening comb. Scale bars 10 mm (A–B), 5 mm (C–E), 1 mm (F–J, M), 0.5 mm (K–L, N–P).

FIGURE 5. Burrow structure of Damarchus pylorus sp. nov. (A–B), of D. lanna sp. nov. (C) and of D. dao sp. nov. (D). (A) Schematic drawing of entire burrow with soil pellet resting in its chamber and leaving access to side shaft; spider sitting in ambush below burrow entrance. (B) Schematic drawing of spider plugging side shaft entrance by pulling soil pellet out of its resting chamber. (C) Schematic drawing of entire burrow with side shaft branching at an angle from main shaft; spider retreated to bottom of main shaft. (D) Schematic drawing of entire burrow with side shaft as a straight continuation of main shaft; an egg sac suspended inside side shaft; spider sitting in ambush behind burrow entrance. Abbreviations: es—egg sac; ms—main shaft; pr—prey remnants; sc—silken collar; ss—side shaft; sp—soil pellet. Scale bars 20 mm.

FIGURE 11. Damarchus dao sp. nov., male holotype. (A) Prosoma, dorsal view. (B) Same, ventral view. (C) Labium and nearby parts of palpal coxae showing peg-like cuspules, ventral view. (D) Opisthosoma, dorsal view. (E) Same, ventral view. (F) Spinnerets, lateral view. (G) Right tibia, metatarsus and tarsus I, prolateral view. (H) Left metatarsus I, proventral view. (I) Coupling spur of left tibia I, proventral view. (J) Same of right tibia I. (K) Distal part of left palp, prolateral view. (L) Same, ventral view. (I) Same, retrolateral view. Scale bars 5 mm (A, D–E, G), 1 mm (B–C, F, H–M).

FIGURE 12. Damarchus dao sp. nov., female allotype. (A) Prosoma, dorsal view. (B) Carapace, lateral view. (C) Prosoma, ventral view. (D) Labium and nearby parts of palpal coxae showing domed cuspules, ventral view. (E) Opisthosoma, dorsal view. (F) Same, ventral view. (G) Tibia and tarsus of left palp, dorsal view; arrow indicating indistinct pseudosegmentation. (H) Tip of left tarsus I showing distinct unpaired claw (absent or indistinct in females of D. pylorus sp. nov.), prolateral view. Scale bars 5 mm (A–B, E–F), 1 mm (C–D, G–H).

FIGURE 13. Damarchus dao sp. nov., vulvae of four females, ventral view. (A) Allotype. (B) Paratype 1. (C) Paratype 2. (D) Paratype 3. Abbreviations: ga—genital atrium; h—head of receptacle; pr—primary receptacle; s—spermatheca; sr—secondary receptacle; st—stalk of receptacle. Scale bars 1 mm.