Thanatus elongatus ( Tikader, 1960 ) Sudhin & Sen & Caleb, 2022

Sudhin, Puthoor Pattammal, Sen, Souvik & Caleb, John T. D., 2022, Taxonomic notes on the placement of Tibellus elongatus Tikader, 1960 and Apollophanes bangalores Tikader, 1963 (Araneae: Philodromidae), Zootaxa 5182 (3), pp. 288-296 : 289-293

Thanatus elongatus ( Tikader, 1960) comb. nov.

Figs 1A–H , 2A–H , 3A–D , 4A–F

Tibellus elongatus Tikader, 1960: 176 , figs 3a–b (description and illustrations of female). Tikader 1971: 82, figs 20E–F (description and illustrations of female); Tikader 1980: 217, figs 288–289 (description and illustrations of female); Tikader & Biswas 1981: 88, figs 152–153 (description and illustrations of female).

Type material. Holotype female from INDIA: West Bengal: Calcutta (now Kolkata), Dhakuria , 01 June 1958, B. K. Tikader ( NZC-ZSI, Kolkata, Regd. No. 2522/18), examined.

Other material examined. INDIA: West Bengal: 1♀ (Regd. No. 2638/18), Calcutta, Pratapgarh, Jadavpur , 19 December 1976, B. Biswas ( NZC-ZSI, Kolkata, a registered male specimen [Regd. No. 2641/18] could not be located in the arachnid collection of ZSI) . Tamil Nadu: 1♂, 2♀♀, Kanyakumari, Kanyakumari Wildlife Sanctuary , 8°27'23.48"N, 77°18'11.26"E, 91 m, 15 February 2020, S. Sen, by hand (NZC-ZSI-7381/18) ; 1♀, 8°22'50.48"N, 77°24'41.26"E, 104 m, 13 February 2020, S. Sen, by hand (NZC-ZSI-7382/18). Kerala: 2♀♀, Thiruvananthapuram, Neyyar Wildlife Sanctuary , 08°32'02"N 77°09'02"E, 82 m, 16 January 2019, P. M. Sureshan, by hand (NZC-ZSI- 7383/18) .

Diagnosis. Thanatus elongatus is characterised by the specific configuration of tibial apophyses and bulbal sclerites of the male palp ( Figs 2A–B , 3A–B ) and the female genitalic structures ( Figs 2C–H , 3C–D ). Currently it cannot be allocated to a particular species group. The male resembles those of some Asian species, above all T. hongkong Song, Zhu & Wu, 1997 , T. pollex Li, Feng & Yang, 2012 , T. fornicatus Simon, 1897 , and T. mongolicus ( Schenkel, 1936) . It can be separated from T. hongkong by the G-shaped sperm duct loop (S-shaped in T. hongkong ), from T. pollex by the compact RTA (elongated and tapering RTA in T. pollex ), from T. fornicatus by the short VTA (VTA longer than RTA in T. fornicatus ) and from T. mongolicus by the robust embolus tip (filiform ventrad tip in T. mongolicus ). The epigyne of Thanatus elongatus resembles those of Thanatus fornicatus Simon, 1897 and Thanatus saraevi Ponomarev, 2007 , but the vulva is strikingly different: glandular heads situated mediolaterally (anterolateral in both T. fornicatus and T. saraevi ); spermathecae almost spherical and separated from each other (with tubular elongation posteriorly and relatively closer to each other in both T. fornicatus and T. saraevi ) (cf. Figs 2A–H , 3A–D with figs 3–8 in Logunov 2011, figs 11–12 in Levy 1991, figs 2B–C in Li et al. 2012, figs 2A–B in Song et al. 1997, and figs 8, 13, 24, 35 in Kastrygina & Kovblyuk 2013).

Justification of transfer. Tikader (1960) described Tibellus elongatus on the basis of a single female specimen collected from Calcutta (now Kolkata). Detailed examination of the holotype, additional specimens from Calcutta and newly collected material including both sexes from South India, show that this species has diagnostic features of Thanatus : oval to elongate body; eyes small, of almost same size; anterior row of eyes distinctly closer together than posterior row of eyes ( Figs 1G–H ); both eye rows moderately recurved, with the posterior row of eyes almost equally spaced ( Figs 1G–H ); legs relatively long; abdomen oval, slightly tapering posteriorly, dorsomedially with dark longitudinal marking ( Figs 1A, D–E ); male palp with simple RTA and VTA; embolus distally on tegulum; epigynum with broad median septum; spermathecae with glandular head ( Levy 1977). Based on the presence of all of these characters, the species is thus transferred to Thanatus .

Description. Male (NZC-ZSI-7381/18) ( Figs 1C–D, H , 2A–B , 3A–B ): Measurements: Body length 5.65. Carapace length 2.54, width 2.16. Abdomen length 3.11, width 1.60. Eye interdistances: AME–AME 0.21, ALE– AME 0.19, PME–PME 0.25, PLE–PME 0.39, ALE–PLE 0.46, AME–PME 0.20, ALE–ALE 0.49, PLE–PLE 0.96. Measurements of legs: I 7.3 [2.08, 0.99, 1.72, 1.48, 1.03], II 8.8 [2.88, 0.81, 1.98, 2.05, 1.08], III 6.37 [2.00, 0.78, 1.67, 1.27, 0.65], IV 6.81 [2.26, 0.73, 1.44, 1.29, 1.09]. Leg formula: 2143. Spination. Palp: femur pl 1 rl 1 do 1 rlv 3, tibia pl 1 rl 1, tarsus pl 2. Legs: femur I–II pl 3 rl 4 do 3, III pl 2 rl 2 do 3, IV pl 1 rl 1 do 3; patella I–IV pl 1; tibia I–III pl 3 rl 3 do 1 plv 3 rlv 3, IV pl 2 rl 2 do 1 plv 2 rlv 2; metatarsus I–II pl 3 rl 3 plv 2 rlv 2, III pl 3 rl 3 do 1 v 1 plv 2 rlv 2, IV pl 4 rl 4 v 1 plv 3 rlv 3; tarsus I–IV spineless.

Carapace pale yellow, flattened, narrowing in front, covered with setae, laterally with dark bands of numerous spots, carapace margin with narrow black dotted lines ( Fig. 1D ); eyes black, small, posterior row more recurved than anterior, PLE larger than other eyes, ocular quad longer than wide ( Fig. 1D ). Clypeus low, pale yellow, covered with black spots. Chelicerae pale yellow, basally with several black spots, promargin with two teeth; fangs small, light-yellowish brown. Endites yellow, longer than wide, scopulate ( Fig. 1C ). Labium yellowish brown, wider than long, with median notch, apically scopulate ( Fig. 1C ). Sternum yellow, nearly cordate, laterally with few black spots, anterior margin straight, posterior margin ending with obtuse tip between coxae IV ( Fig. 1C ). Legs yellow with black spots, more densely spotted on lateral side; tarsi, metatarsi with conspicuous scapulae, claw tuft distinct. Abdomen elongate oval, yellow with white reticulation and several lateral black spots; dorsum medially with a longitudinal black dotted line extending the entire length of the abdomen and four pairs of similar transverse parallel lines stretching from the median line to the lateral margins; dorsum with two pairs of sigilla, anteriorly with two pairs of black markings, medially with a round black patch, and posteromedially with a pair of conspicuous black patches ( Fig. 1D ); venter yellow, with white reticulations and a faint median white band ( Fig. 1C ). Palp as shown in Figs 2A–B , 3A–B : tegulum yellowish brown, rest of the segments pale yellow; cymbium long oval with a prolateral ventral spine and numerous short white setae; tegulum oval without tegular apophysis, ‘G’ shaped sperm duct loop visible on the middle of tegulum ( Figs 2B , 3B ); embolus hook-shaped, situated distally on tegulum, near the 12 o’clock position, with the acute tip curving inwards towards the tegulum ( Figs 2B , 3B ); tibia with short and membranous VTA, RTA basally broad, tip blunt, not suppressing the basal part of cymbium ( Figs 2A , 3A ).

Redescription. Female (NZC-ZSI-7381/18) ( Figs 1A–B, E–G , 2C–H , 3C–D , 4A–D ): Measurements: Body length 7.62. Carapace length 2.31, width 2.24. Abdomen length 5.31, width 2.99. Eye interdistances: AME–AME 0.18, ALE–AME 0.17, PME–PME 0.28, PLE–PME 0.39, ALE–PLE 0.48, AME–PME 0.20, ALE–ALE 0.50, PLE– PLE 1.0. Measurements of legs: I 7.9 [2.56, 0.93, 1.98, 1.64, 0.79], II 9.71 [2.76, 0.92, 2.46, 2.37, 1.20], III 5.47 [1.66, 0.82, 1.45, 0.92, 0.62]; IV 7.02 [1.85, 0.93, 1.95 1.24, 1.05]. Leg formula: 2143. Spination. Palp: femur pl 1 rl 1 do 1 rlv 3 plv 1, patella pl 1 rl 1, tibia pl 2 rl 2 plv 3, tarsus plv 4 rlv 4; Legs: femur I–II pl 3 rl 4 do 3, III–IV pl 2 rl 2 do 3; patella I–IV pl 1; tibia I–IV pl 3 rl 3 do 1 plv 3 rlv 3; metatarsus I– II pl 3 rl 3 plv 2 rlv 2, III–IV pl 3 rl 3 plv 3 rlv 3; tarsus I–IV spineless.

Colouration as in male, except for the following: carapace light yellowish brown, laterally with dense black spots ( Fig. 1A ). Sternum medially with several black spots ( Fig. 1B ). Abdomen longer and wider with more prominent white reticulation ( Fig. 1A ). Epigyne as shown in Figs 2C–H , 3C–D . Epigyne with broad, ‘U’ shaped, median septum, copulatory opening located laterally to the septum ( Figs 2C, F, H , 3C ); spermathecae almost spherical, posteriorly narrowing, separated from each other, with a mediolaterally situated glandular head ( Figs 2C, E, G , 3C, D ); fertilization ducts long, leaf like, oriented anterolaterally, situated at the posterior region of spermathecae ( Figs 2E, G , 3D ).

Distribution. India: Kerala (NWS), Maharashtra (Pune), Tamil Nadu (Chennai, KWS), West Bengal (Dhakuria – type locality; Pratapgarh) ( Tikader 1960; Tikader 1971; Tikader & Biswas 1981; Caleb 2020; present data) ( Fig. 6 ).

Variation. Body length: Female: 6.92–7.60 (n=3). The abdominal patterns of the specimen collected from NWS are composed of dark brown stripes, while of the specimens collected from KWS are composed of numerous black spots ( Figs 1A, E ).

Figures

FIGURES 1A–H. Somatic morphology of Thanatus elongatus (Tikader, 1960) comb. nov. A–B, G Female from KWS (A dorsal, B ventral, G prosoma frontal); C–D, H Male from KWS (C ventral, D dorsal, H prosoma frontal); E–F Female from NWS (E dorsal, F ventral). Scale bars: A–F: 2 mm. G–H: 0.5 mm.

FIGURES 2A–H. Genital morphology of Thanatus elongatus (Tikader, 1960) comb. nov. A–B Left male palp (A retrolateral, B ventral); C–E Female epigyne from KWS (C ventral, D ventral, cleared, E dorsal); F–G Female epigyne from NWS (F ventral, G dorsal); H Epigyne (holotype), ventral. Scale bars: A–H: 0.2 mm.

FIGURES 3A–D. Genital morphology of Thanatus elongatus (Tikader, 1960) comb. nov. A–B Left male palp (A retrolateral, B ventral); C–D Female epigyne (C ventral, D dorsal). Scale bars: A–D: 0.2 mm.

FIGURES 4A–F. Thanatus elongatus (Tikader, 1960) comb. nov. A, C, E Holotype female (A habitus dorsal, C venter/ epigyne, ventral, E label); B, D, F Female from Pratapgarh (B habitus dorsal, D venter/epigyne, F label). Scale bars: A–B: 2 mm. C–D: 1 mm.

FIGURE 6. Map showing the distributional records of Thanatus elongatus (Tikader, 1960) comb. nov. Yellow star indicates the type locality.