Psellonus planus Simon, 1897

Malamel, Jobi J., Nafin, Karunnappilli Shamsudheen, Sankaran, Pradeep M. & Sebastian, Pothalil A., 2019, Taxonomic revision of the monotypic genus Psellonus Simon, 1897 (Araneae, Philodromidae), Zootaxa 4543 (3), pp. 442-450 : 443-449

Psellonus planus Simon, 1897

( Figs. 1–4 )

Psellonus planus Simon, 1897: 14 , figs 9–10 (Holotype female from Madurai, Tamil Nadu, India, not traceable at MNHN [Muséum national d’histoire naturelle, Paris], personal communication through C. Rollard, not examined).

Philodromus kendrabatai Tikader, 1966: 38 , fig. 3 (Holotype female from Peacock bay, N. D. A., Kharakvasla, Poona, Maharashtra, India, deposited in National Zoological Collections, Zoological Survey of India, Calcutta, No. 3134/18, examined). Tikader 1971: 72, figs 19A, B; Tikader 1980: 191, figs 261–262. Syn. nov.

Material examined. INDIA: Kerala: 11 males, 25 females, Alappuzha, Pathiramanal Island [9 o 37'08.27''N, 76 o 23'23.86''E], 0 m, 15 March 2014, 22 April 2014, 17 May 2014, 8 November 2014, January 2015, from foliage, by hand, leg., M.J. Jobi & Jimmy Paul ; 14 males, 27 females, 12 subadult males, 20 subadult females, Alappuzha, Perumbalam [9 o 50'54.13''N, 76 o 21'39.00''E], 10 m, 24 November 2015, 16 December 2015, 9 January 2016, 11 February 2016, 7 March 2016, from foliage, by hand, leg., M.J. Jobi & Jimmy Paul ; 8 males, 16 females, 7 subadult males, 13 subadult females, Alappuzha, Kayipuram [9 o 37'41.22''N, 76 o 22'10.03''E], 12 m, 12 October 2015, 16 November 2015, 16 January 2016, 18 February 2016, 19 March 2016, from foliage, by hand, leg., M.J. Jobi & Jimmy Paul ; 13 males, 18 females, 11 subadult males, 19 subadult females, Ernakulam, Thevara [9 o 56'33.40''N, 76 o 17'54.94''E], 7 m, 16 September 2015, 22 November 2015, 16 December 2016, 3 January 2016, 9 February 2016, from foliage, by hand, leg., M.J. Jobi ; 1 male, 2 females, 4 subadult females, Thrissur, Irinjalakuda [10 o 20'40.80''N, 76 o 12'33.74''E], 15 m, 12 November 2015, from foliage, by hand, leg., K.S Nafin ; 2 females, Thrissur, Muriyad [10 o 21'48.95''N, 76 o 15'44.62''E], 8 m, 7 December 2015, from foliage, by hand, leg., K.S Nafin ; 2 females, Wayanad, Wayanad Wildlife Sanctuary [11 o 40'17.76''N, 76 o 22'07.16''E], 863 m, 7 January 2016, from foliage, by hand, leg., K.S Nafin & Sudhin . Tamil Nadu: 1 male, 2 females, 10 subadult males , 14 subadult females, Madurai, Thirumangalam [9 o 49'24.09''N, 77 o 59'17.13''E], 130 m, 22 December 2015, from foliage, by hand, leg., M.J. Jobi (all material ADSH) .

Description. Male (from Thirumangalam):

Prosoma orange-yellow colored, hirsute, wider than long, forehead straight and truncated in the front, gradually expanded towards the back and largely truncated at the posterior, surface of the prosoma marked by fine stripes like rainbow, prosoma laterally clothed with fine bristles ( Figs. 1 A–D, 2A); eyes occupying the entire width of clypeus, anterior eye row almost a straight line, equally spaced, posterior eye row recurved, all eyes equal in size except for the very small PME ( Fig. 2C ); chelicerae strongly divergent, basal segment almost triangular with prominent dorsal hump, cheliceral furrow teethless ( Fig. 2C ); sternum straw colored, anteriorly broadly truncated ( Fig. 2B ); gnathocoxae strongly elongated, labium tongue like, twice as long as wide ( Fig. 2B ); leg formula 2314, spination variable and often asymmetric, but generally femora with 3–5 dorsal spines, tibiae I–II with 3–5 pairs of ventral spines and metatarsi I–II with two pairs of ventral spines. Opisthosoma straw colored, hirsute, longer than wide, narrow and parallel, wedge-shaped at the back, with tuft of hairs at the posterior end, two pairs of depression spots in the anterior half ( Figs. 1 A–D, 2A); venter smooth, a pair of depressions just before the spinnerets ( Fig. 2B ). Palp ( Figs. 2 D–F). Femur long, patella thick, tibia more than twice as long as wide, with numerous macrosetae and 2-3 trichobothria, RTA short, bifurcated; cymbium drop-like, covered with fine hairs, apical region with a bunch of tenent setae; tegulum oval with retrolaterally projecting apophysis; embolus with wide embolic base and narrow bent tip; sperm duct convoluted.

Measurements of palp and legs:

Female (from Thirumangalam): Prosoma straw colored, appearing transparent ( Figs. 1 E–H); eyes on white tubercles, except PME that are very small, largely separated from the lateral ones ( Fig. 3A ); venter smooth, sternum almost round ( Fig. 3B ); chelicerae conical shaped with very large, prominent dorsal hump, cheliceral promargin with one apical tooth ( Fig. 3C ); dorsum of tibiae, metatarsi and tarsi of the first three legs irregularly covered with short bristles, spination as in male, legs III and IV without spines, metatarsus of leg IV with conspicuous hair tuft; opisthosoma less hairy than in male, not smooth, with comma-shaped black patches posteriolaterally; median spinnerets covered with some black spots. Epigyne ( Figs. 3D,E ): epigynal groove with anteriorly elongated, sclerotized epigynal sutures, spermathecae globular, SPO on distinct stalks, FD elongated, CD very short, indistinct.

Measurements of legs:

Natural History. Immature specimens of this species are very fast runners. Frequently we observed preballooning tiptoe behavior ( Figs. 4 A–H) and realized wind carriage over long distances. Adult spiders may easily be caught when they rest in the foliage.

Distribution. Verified distribution records of Psellonus planus from South India: Tamil Nadu (Madurai, Thirumangalam) and Kerala (Kayipuram, Irinjalakuda, Muriyadu, Pathiramanal Island, Perumbalam Island, Thevara, Wayanad) are shown in a map ( Fig. 5). Tikader (1966) recorded Philodromus kendrabatai from the Indian states Maharashtra and Karnataka, indicating that the species may be more widespread in India.

Remarks. Simon (1897) described the monotypic genus Psellonus to accommodate the single species P. planus based on a single male sex from Madurai and placed the genus in the family Philodromidae . He recognized similarities with Plator Simon (Fam. Trochanteriidae Karsch ) and Selenops Latreille (Fam. Selenopidae Simon ), and due to the unique character configuration he erected the monogeneric subfamily Pselloninae. In the original description of Psellonus, Simon (1897) focused on somatic morphological characters. Our description of genitalic features in both sexes corroborates the inclusion of Psellonus in the family Philodromidae . Moreover, we record the presence of tenant setae with truncate tip at the palpal tarsus, a synapomorphy for Philodomidae recently proposed by Ramirez (2014).

Since the original description, no other species have been added to the genus. The original drawings and descriptive characters given for Philodromus kendrabatai Tikader, 1966 suggested that it may be conspecific with Psellonus planus . Examination of the type material confirmed this new synonymy. Among our material of P. planus , we observed remarkable variation in somatic (size, coloration, leg spination) and genitalic characters (most evident in the curvature of the sperm duct, but also in details of RTA, embolus, spermathecae and spermathecal organs). Since morphological variation did not show a geographical pattern, we consider the variation intraspecific. However, we cannot exclude the possibility that Psellonus planus could constitute a complex of cryptic species.

Psellonus shows remarkable similarity with the genus Pedinopistha Karsch , endemic to the Hawaiian Islands. The relationship has already been discussed by Simon (1899, 1900), but finally Simon (1900) considered Pedinopistha more closely related to Philodrominae than Pselloninae. Comprehensive phylogenetic studies are required to resolve the relationships of these genera and their placement within Philodromidae .

Figures

FIGURES 1A–H. Field photographs of Psellonus planus. A–D male; E–H female. Photo credit: Mr. Jimmy Paul.

FIGURES 2A–F. Psellonus planus. Male. A–B habitus (A dorsal, B ventral); C chelicerae, dorsal; D–F left pedipalp (D ventral, E retro-lateral, F pro-lateral). Scale bars: A 0.5 mm, B 0.3 mm, C 0.1 mm, D–F 0.2 mm. Abbreviations: E—embolus; RTA—retrolateral tibial apophysis; S—subtegulum; SP—sperm duct; T—tegulum; TA—tegular apophysis.

FIGURES 3A–E. Psellonus planus. Female. A–B habitus (A dorsal, B ventral); C chelicerae, dorsal; D epigyne, ventral; E vulva, dorsal. Scale bars: A 0.5 mm, A 0.5 mm, B 0.3 mm, C 0.2 mm, D 0.1 mm, E 0.05 mm. Abbreviations: FD—fertilization duct; SPM—spermathecae; SPO—spermathecal organ.

FIGURES 4A–H. Natural history of Psellonus planus. Photo credit: Mr. Jimmy Paul