Paktongius spiculosus, Klementz & Sharma, 2023

Klementz, Benjamin C. & Sharma, Prashant P., 2023, New species of Paktongius and convergent evolution of the gonyleptoid-like habitus in Southeast Asian Assamiidae (Opiliones: Laniatores), Zootaxa 5389 (1), pp. 34-54 : 40-44

Paktongius spiculosus sp. nov.

( Figs. 4–6 , 11 , 12 ; Tables 3–4 )

Type material. Holotype. ♀ ( MHNG LT-10 /18) LAOS, Khammouan Province, Nam Kading NPA, Tad Mouang, ca. 1km northeast of Nahin , 18°13’13”N, 104°32’08”E, 270 m, disturbed primary forest, 26.ix.2010, leg. P. Schwendinger. L2-4 extracted for DNA; one of each appendage (L1-4; chelicera), both pedipalps dissected and mounted for SEM imaging.

Paratypes. ♂ ( UWZM Y.40171) Same collecting data as holotype. LAOS, Bolikhamxai Province, Phou Khao Khouay NPA, north of Ban Hadkhai , trail to Tad Xay , 18°27’05”N, 103°08’59”E, 300 m (secondary forest), 22.ix.2010, leg. P. Schwendinger. LT-10 /15. Genitalia and one of each appendage dissected and mounted for SEM imaging .

Etymology. The species epithet is derived from the Latin for “spike” (spiculo) and highlights the prominent cluster of tubercles adorning the anal plate of the male, reminiscent of thorns or spikes.

Diagnosis. Distinguished from congeners by the combination of the following characters:(1) dorsal pigmentation composed of solid dark patches that do not cross dorsal midline (contra rings in P. suzukii , P. paritensis , P. furculus ; anterior-most patches crossing midline in P. thaiensis ); (2) ventral pigmentation posterior to the genital operculum constituting subtriangular shape, without prominent “wings”; (3) absence of two distinct lines of pigment stretching posteriorly from the ocularium (contra P. furculus , P. paritensis ); (4) presence of eight enlarged tubercles on the anal plate (males only); (5) absence of enlarged tubercles along the posterior margin of the scutum; (6) tarsal formula: 5: 9: 6: 6. Males additionally distinguished from congeners by the combination of three enlarged tubercles on the lateral margin of the leg IV femur (contra P. suzukii ), and genitalia with five pairs of lateral setae (contra P. suzukii ) and two dorso-apical cuticular projections (contra P. thaiensis ).

Description. Total length of female holotype (male paratype in parentheses) 2.56 mm (2.98 mm), greatest width of the prosoma 1.23 mm (1.28 mm), greatest width of the opisthosoma 2.20 mm (2.34 mm); length-to-width ratio 1.16 (1.27). Body campaniform with sub-rectangular posterior margin ( Fig. 4 ). Body reddish brown in color with darker mottling (in alcohol, depending on incidence of light) in holotype, almost entirely with a dense microgranulate surface microstructure. Eyes present on small, unornamented ocularium that is set back from anterior margin of the carapace. Ocularium 0.24 mm (0.23 mm) long, 0.30 mm (0.32 mm) wide. Anterior margin of carapace with five pegs (two pairs on lateral margins, one at the dorsal midline), typical of Assamiidae . Scutal grooves of mesotergum indistinct. Scutal areas III–IV with pairs of small spines flanking the midline. Free tergites unarmed.

Ventral prosoma complex ( Fig. 4b, d ) of male and female, with coxae II and III meeting in midline, coxae I not so. Genital operculum subtriangular in male, elliptical in female. Spiracles not apparent. Coxae IV of both male and female massively enlarged (for Grassatores).Anal plate armed with eight prominent tubercles in male, same number of small and blunt tubercles in female.

Dorsal pigmentation of male absent (likely due to recent ecdysis event) ( Fig. 4c, d ). Dorsal pigmentation of female with continuous band of pigment along lateral margins of the carapace ( Fig. 4a, b ); mottled rings of dark pigmentation immediately posterior to ocularium; solid wing-shaped patches of pigmentation on scutal areas I–IV flanking the midline; and dark patches of pigmentation on both lateral pairs of pegs at anterior margin of the carapace. Ventral pigmentation of female indistinct except along ventral midline of opisthosomal segment II (between coxae IV), lateral margins of coxae IV, and flanking the midline at the posterior of coxae IV. Sternites posterior to opisthosomal segment II uniformly with darker pigmentation.

Chelicerae ( Figs. 5a , 6a ) sexually monomorphic, with prominent bulla on proximal article. Proximal article with denticulate granulation basally and ventrally. Second article not incrassate, free of ornamentation, with dorsal and latero-distal margin bearing several setae. Distal article with delicate dentition, free of ornamentation. Pedipalps ( Fig. 5b–c , 6b ) spoon-shaped and folded over chelicerae. Pedipalpal trochanter slender with two prominent setose tubercles at ventro-distal margin. Pedipalpal femur ventrally with eight small tubercles, lacking megaspines and located in proximal half of femur; dorsally with small setose tubercles distally. Pedipalpal tibia with two ventrally oriented spines at the distal margin and one smaller spine at a ventro-lateral and proximal position. Spine length 0.23 mm (0.21 mm). Pedipalpal tarsus with four megaspines and unornamented tarsal claw. Legs I–IV ( Fig. 5d–g , 6c–f ) slender, elongate, finely granulated, with small and irregularly distributed setiferous tubercles on femora, patellae, tibiae, and metatarsi. Femur I of both male and female ventrally with prominent row of setose tubercles. Coxa II of both male and female with prominently projecting pegs, particularly at the posterior of trochanter II. Male femur IV ectally with four prominent setiferous tubercles (not present in female). Tarsal claws I–IV smooth, unmodified, double claws on legs III and IV (typical of Grassatores). Legs III and IV with tarsal process ( Fig. 11b ). Tarsal formula 5: 9: 6: 6.

Male genitalia ( Fig. 6g –h ) typical of Assamiidae , with two cuticular dorsal projections distally; two pairs of apical setae; five pairs of setae on lateral margins of ventral plate; three pairs of setae on ventral plate.

Distribution. Known from Khammouan and Bolikhamxai Provinces, Laos ( Fig. 12 ).

Figures

FIGURE 4. Paktongius spiculosus sp. nov. Female holotype, dorsal view (a). Female holotype, ventral view (b). Male paratype, dorsal view (c). Male paratype, ventral view (d). Scale bars: 1.0 mm.

FIGURE 5. Paktongius spiculosus sp. nov. Appendages are presented in ectal view unless otherwise indicated. Left chelicera of female holotype (a). Left pedipalp of female holotype (b). Right pedipalp of female holotype, mesal view (c). Left leg I of female holotype (d). Left leg II of female holotype (e). Left leg III of female holotype (f). Left leg IV of female holotype (g). Scale bars: 500 µm (a–c), 1 mm (d–g).

FIGURE 6. Paktongius spiculosus sp. nov. Appendages are presented in ectal view unless otherwise indicated. Left chelicera of male paratype (a). Left pedipalp of male paratype (b). Left leg I of male paratype (c). Left leg II of male paratype (d). Left leg III of male paratype (e). Left leg IV of male paratype (f). Genitalia of male paratype, dorsal view (g). Genitalia of male paratype, ventral view (h). Scale bars: 500 µm (a–b), 1 mm (c–d), 2 mm (e–f), 100 µm (g–h).

FIGURE 11. Condition of the leg IV tarsal process in all newly described Paktongius species. Paktongius suzukii sp. nov., left leg IV of female paratype (a). Paktongius spiculosus sp. nov., left leg IV of male paratype (b). Paktongius paritensis sp.nov., left leg IV of female holotype (c). Paktongius furculus sp. nov., left leg IV tarsus of female holotype (d). Location of tarsal process indicated by white arrowheads. Scale bars: 100 µm.

FIGURE 12. Distribution of Paktongius species in the Thai-Malay Peninsula. Icons correspond to the following species: star: Paktongius suzukii sp. nov.; circle: Paktongius spiculosus sp. nov.; square: Paktongius paritensis sp. nov.; triangle: Paktongius furculus sp. nov.; pentagon: Paktongius distinctus Suzuki, 1969; ten-pointed star: Paktongius thaiensis (Suzuki, 1985) comb. nov.