Paktongius furculus, 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 : 47-51

Paktongius furculus sp. nov.

( Figs. 9–12 ; Table 6 )

Bandona sp. , Palmieri et al. 2023

Type material. Holotype. ♀ ( MCZ 92229 ), Thailand, Kanchanaburi: Khuean Srinagarindra NP, tourist center, 16–17.viii.2008, 14°38.136’N, 98°59.837’E. Chatchawan, Boonkam, collectors. Field Number: T3433 . Collection method: pan trap. L2-3 extracted for DNA; one of each appendage dissected and mounted for SEM imaging.

Etymology. The species epithet is derived from the Latin for “wishbone” (furculum) and highlights the prominent pigmentation along the ventral midline and posteriolateral margins of the leg IV coxae, superficially resembling a bird wishbone or furcula.

Diagnosis. Distinguished from congeners by the combination of the following characters: (1) dorsal surface of scutum areas I–IV with rings of dark pigmentation that overlap the midline (contra solid patches in P. distinctus , P. spiculosus , P. thaiensis ; rings not overlapping midline in P. furculus , P. suzukii ); (2) ventral pigmentation posterior to genital operculum constituting a central column with attached, thin wings, and a small posterior projection at the midline; (3) presence of distinct lines of pigment stretching posteriorly from the ocularium (contra P. distinctus , P. spiculosus , P. suzukii , P. thaiensis ); (4) presence of two to three enlarged tubercles along the anterolateral margins of the fourth coxae (contra P. suzukii , P. spiculosus , P. thaiensis ); (5) absence of enlarged tubercles on the anal plate (contra P. thaiensis , male P. spiculosus ); (6) tarsal formula: 5: 9: 6: 6.

Description. Female holotype, total length 2.88 mm, greatest width of prosoma 1.09 mm, greatest width of opisthosoma 1.89 mm; length-to-width ratio 1.52. Body shape pandurate (fiddle-shaped; Fig. 9 ). Body reddishbrown in color with darker mottling, densely microgranulate surface microstructure. Eyes present on small ocularium with a single enlarged tubercle, set back from anterior margin of the carapace. Ocularium 0.15 mm long, 0.23 mm wide. Anterior margin of carapace with five pegs (two pairs on lateral margins with outermost longest, one at dorsal midline), typical of Assamiidae . Anterior margin of carapace also adorned with a single row of slightly enlarged tubercles, most prominent at the dorsal midline. Final three segments of scutum each with rows of slightly enlarged tubercles, largest of which flanking midline and projecting posteriorly. Free tergite III also with two prominent spines flanking midline. Free tergite I and II with eight enlarged tubercles, four on either side of dorsal midline.

Ventral prosomal complex ( Fig. 9b ) with coxae II and III meeting in midline, coxae I not so. Genital operculum sub-triangular to reniform. Spiracles not apparent. Coxae IV highly enlarged (typical of Grassatores) and with enlarged tubercles along anterolateral margin. Coxae IV also with single enlarged tubercle laterally at junction with trochanter IV and projecting posteriorly. Posterior-most tergite with two tubercles projecting ventrally. Anal plate unarmed.

Dorsal pigmentation with continuous band of dark pigment along lateral margin of the carapace; two solid patches of pigment flanking anterior-posterior axis immediately posterior to the ocularium; two arcuate patches of pigment toward posterior-lateral margin of the prosoma; prominent arcuate rings of pigmentation on scutal areas I–IV overlapping the midline; pegs above pedipalpal coxae pigmented; and anterior margins of free tergites with stripes of pigment. Ventral pigmentation prominently flanking ventral midline of opisthosomal segment II and the posterior margins of the leg IV coxae, creating a winged-shape with prominent anterior projection. Leg IV coxae also with arched bands of pigment extending posteriorly to the junction of the leg IV trochanter; patches of pigment medially; and patches of pigment at posterior margin near trochanter. Pigmentation of coxae I–III consisting of indistinct mottling. Sternites with stripes of pigmentation at anterior margins.

Chelicerae ( Fig. 10a ) with prominent bulla on proximal article. Proximal article with denticulate granulation throughout basal territory with notable smoothening of the cuticle towards the dorsal side of the bulla. Proximal article sparsely setose. Second article not incrassate, smooth, free of ornamentation. Several prominent setae along the length of the dorsal territory and along margin of distal article. Distal article with delicate dentition, free of ornamentation. Pedipalps ( Fig. 10b ) spoon-shaped and folded over chelicerae. Pedipalpal trochanter slender with two prominent setose tubercles at ventro-distal margin. Femur ventrally with a series of eight small, adjacent tubercles, lacking megaspines, restricted to proximal-most territory, and an additional disjunct tubercle midway along ventral surface. Femur dorsally with small setose tubercles toward distal end. Pedipalpal tibia with two megaspines, one ventrally oriented at apex of prominent triangular projection, other dorso-laterally oriented. Laterally, tibia also with exaggerated proximal megaspine. Sparsely setose ventrally and laterally. Pedipalpal tarsus with unornamented tarsal claw and four megaspines ventro-distally, two flanking each side of the claw. Tarsal claw 0.25 mm long. Legs I–IV ( Fig. 10c–f ) slender, elongate, finely granulated, and with setiferous tubercles roughly arranged into rows along femora, patellae, tibiae, and metatarsi. Leg I trochanter with several notable cuticular projections. Tarsal claws I–IV smooth, unmodified, double claws on legs III and IV (typical of Grassatores). Legs III and IV with tarsal process ( Fig. 11d ). Tarsal formula 5: 9: 6: 6.

Male. Unknown.

Distribution. Known only from the type locality ( Fig. 12 ).

Figures

FIGURE 9. Paktongius furculus sp. nov. Female holotype, dorsal view (a). Female holotype, ventral view (b). Scale bars: 1.0 mm.

FIGURE 10. Paktongius furculus sp. nov. Appendages are presented in ectal view unless otherwise indicated. Left chelicera of female holotype (a). Left pedipalp of female holotype (b). Left leg I of female holotype (c). Left leg II of female holotype (d). Left leg III of female holotype (e). Left leg IV of female holotype (f). Scale bars: 500 µm (a–b), 1 mm (c, e), 2 mm (d, f).

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.