Rhitymna gerdmangel, Jäger, 2019

Jäger, Peter, 2019, Review of the huntsman spider genus Rhitymna Simon, 1897 (Araneae: Sparassidae), Zootaxa 4560 (3), pp. 441-462 : 442-446

Rhitymna gerdmangel spec. nov.

Figs 1–8 , 16–19 , 28 , 61

Type material. Holotype male ( PJ 3637 ): THAILAND: Mae Hong Son Province: close to Ban Nam Rin [N 19°27'18.42", E 98°16' 60.00", 940 m elevation], felled bamboo, D. Kovac leg. September 2003 (SMF). Paratypes (6 males, 8 females): THAILAND: Mae Hong Son Province: 1 female ( PJ 3641 ), same data as holotype, but: upright old bamboo stem on the way to cave, Cephalostachyum pergracile, 9 April 2003 (SMF); 1 male ( PJ 3642 ), close to Ban Pha Mon [19°31'51"N, 98°17'51"E, 910 m elevation], in bamboo stem, D. Kovac leg. 16 June 2006,

G6/06 (SMF); 1 male ( PJ 3643 ) , same data as holotype, but: 21 September 2003 ( SMF) ; 1 male ( PJ 3644 ) , same data as holotype, but: 18 September 2003 ( MHNG) ; 1 female ( PJ 3645 ) , same data as holotype, but: upright old bamboo stem, Cephalostachyum pergracile, 9 April 2003, with egg sac including ca . 40 eggs ( SMF) ; 1 female ( PJ 3646 ) , same data as holotype, but: upright old bamboo stem, Cephalostachyum pergracile, 4 April 2003, with egg sac including ca . 25 eggs ( SMF) ; 1 male ( PJ 3647 ) , same data as holotype, but: 23 September 2003 ( CBEE) ; 1 female ( PJ 3648 ) , same data as holotype, but: upright old bamboo stem, Cephalostachyum pergracile, 8 April 2003, with 49 nymphs + 2 insect pupae ( SMF) ; 1 female ( PJ 3649 ) , same data as holotype, but: 18 September 2003 ( SMF) ; 1 female ( PJ 3650 ) , same data as holotype, but: upright old bamboo stem, Cephalostachyum pergracile, 3 April 2003, with 108 eggs + nymphs ( CBEE) ; 1 female ( PJ 3651 ) , same data as holotype, but: upright old bamboo stem, Cephalostachyum pergracile, 30 March–7 April 2003, with ca . 90 eggs in egg-sac ( ZMH) ; 1 male ( PJ 3652 ) , same data as holotype, but: 18 September 2003 ( ZMH) ; 1 female ( PJ 3653 ) , same data as holotype, but: 18 September 2003 ( SMF) ; 1 male ( PJ 3654 ) , 1 female ( PJ 3655 ) , same data as holotype ( SMF) .

Additional material examined (1 male, 4 females, 2 subadult males, 9 subadult females, 9 juveniles): THAILAND: Mae Hong Son Province : 1 subadult female, same data as holotype, but: 21 September 2003 ( SMF) ; 1 subadult male, 1 subadult female, same data as holotype, but: 18 September 2003 ( ZMH) ; 3 subadult females, same data as holotype, but: 18 September 2003 ( SMF) ; 1 subadult female ( PJ 3656 ) , same data as holotype ( SMF) ; 1 subadult female, 5 juveniles, same data as holotype, but: close to Soppong, way to cave, old upright bamboo stem, Cephalostachyum pergracile, 9 April 2003 ( SMF) ; 1 juvenile, same data as holotype, but: from artificially modified internodes made for field experiments, 24.–26 March 2003 ( SMF) ; 2 juveniles, same data as holotype, but close to Soppong , way to cave, old upright bamboo stem, Cephalostachyum pergracile, 23 April 2003 ( SMF) ; 1 subadult female, same data as holotype, but: upright bamboo stem, 21.–22 April 2003 ( SMF) ; 1 subadult male, 1 subadult female, same data as holotype, but: 24 September 2003 ( SMF) . MALAYSIA: Pahang State : 1 male ( PJ 3660 ) , 1 subadult female, Ulu Gombak Research Station [N 3°19'30.00", E 101°54'10.80" E, 1022 m elevation], upright bamboo stem, B11/16, #6, D. Kovac. leg. 10 September 1994 ( SMF) ; 1 female ( PJ 3661 ) , as preceding specimens, B10/16, #4, D. Kovac. leg. 8 September 1994 ( SMF) ; 1 female ( PJ 3659 ) , Ulu Gombak Research Station [N 3°19'30.00", E 101°54'10.80" E, 1022 m elevation], upright bamboo stem, internode with Abryna -hole, D. Kovac. leg. 18 October 1996 ( SMF) ; 1 female ( PJ 3657 ) , Ulu Gombak Research Station [N 3°19'30.00", E 101°54'10.80" E, 1022 m elevation], D. Kovac. leg., without date, Coll. Deeleman ( RMNH) ; 1 female ( PJ 3658 ) , Pahang Road 6, 0.5 miles north of Kuala Lumpur, Scrub Typhus Unit, Robert Traub leg. March– April 1950 ( AMNH) . 1 juvenile, Ulu Gombak Research Station [N 3°19'30.00", E 101°54'10.80" E, 1022 m elevation], D. Kovac. leg. 10 September 1994 ( SMF) .

Etymology. The species is named in honour of Mr Gerd Mangel: as construction manager he was in charge of the renovation and relocation of the scientific collections into the new Senckenberg buildings, a mega task he managed for many years with patience, experience and wisdom; name in apposition.

Diagnosis. Medium-sized to large Sparassidae (body length of males: 11.0–16.3, females: 13.8–21.5). Males of this new species ( Figs 1–5 ) are distinguished from those of all other congeners except R. plana by the embolus arising in distal half of tegulum, a strong dorsal embolic apophysis and a spermophor with distinct bent in medioretrolateral position, but distinguished from the latter by the presence of an additional ventral embolic apophysis, the wider embolic distal loop extending from prolateral to retrolateral, and the larger and distinctly bent dorsal embolic apophysis (without additional embolic apophysis, distal embolic loop smaller and restricted to retrolateral half, dorsal embolic apophysis shorter and straight in R. plana ). Females are distinguished from those of all other Rhitymna species by a unique set of margins within the epigynal plate, forming roughly a rhombus with anterior margins bulged medially ( Fig. 6 ).

Description. Male (holotype): PL 5.1, PW 5.0, AW 4.2, OL 10.4, OW 3.9. Eyes: AME 0.35, ALE 0.31, PME 0.25, PLE 0.29, AME–AME 0.20, AME–ALE 0.40, PME–PME 0.51, PME–PLE 0.68, AME–PME 0.17, ALE– PLE 0.20, clypeus height at AME 0.05, clypeus height at ALE 0.10. Cheliceral furrow with 3 promarginal, 3/4 retromarginal teeth, without denticles. Retromargin of chelicerae close to fang base with 5–6 bristles. Spination: Palp: 131, 0 0 0, 1101; legs: femur I–III 323, IV 322; patella I–III 101, IV 100; tibia I 2026, II 2326, III–IV 2126; metatarsus I–II 2024, III 3024, IV 3035. Leg formula: 2143. Measurements of palp and legs: Palp 7.9 (2.5, 1.1, 1.5, -, 2.8), I 35.1 (9.7, 3.4, 10.1, 9.7, 2.2), II 37.3 (10.1, 3.2, 11.3, 10.3, 2.4), III 23.3 (7.2, 2.4, 6.5, 5.4, 1.8), IV 29.3 (8.7, 2.5, 8.2, 7.8, 2.1). Metatarsi III–IV with ventro-distal spine within scopula.

Palp as in diagnosis ( Figs 1–5 ). Cymbium distinctly longer than tibia. RTA strongly developed with rounded tip in retrolateral view, arising distally from tibia. Embolus arising in 10-o’clock-position from tegulum, with massive base and distal part curving semicircular, in the centre of this loop a pointed and flat ventral embolic apophysis, arising in a 12.30-o’clock-position. Dorsal embolic apophysis hollow and almost entirely hidden in resting position dorsal of embolus and tegulum, with strongly serrated margin at disto-basal part and less serrated at its tip. Spermophor visible in proximal two-thirds of tegulum, and in distal loop of embolus.

Colouration ( Figs 16–17 ). Yellowish- to light reddish-brown. Prosoma with dark fovea, striae slightly marked. Chelicerae deep reddish-brown. Sternum yellowish-brown with distinct dark margin, gnathocoxae and labium brown. Legs yellowish brown with distal segments reddish-brown. Opisthosoma yellowish-brown with typical dark tuning-fork pattern dorsally.

Female (paratype, PJ 3641): PL 8.9, PW 5.6, AW 5.8, OL 12.0, OW 6.2. Eyes: AME 0.55, ALE 0.48, PME 0.33, PLE 0.40, AME–AME 0.30, AME–ALE 0.90, PME–PME 0.86, PME–PLE 1.13, AME–PME 0.23, ALE– PLE 0.32, clypeus height at AME 0.20, clypeus height at ALE 0.12. Cheliceral furrow with 3 promarginal, 4 retromarginal teeth, without denticles. Retromargin of chelicerae close to fang base with 6–7 bristles. Spination: Palp: 131, 0 0 1, 1111, 1011; legs: femur I 323(4), II–III 323, IV 322(1); patella I–IV 101; tibia I–II 2226, III–IV 2126; metatarsus I–II 2024, III 3025, IV 3036(5). Leg formula: 2143. Measurements of palp and legs: Palp 13.7 (4.0, 21, 3.1, -, 4.5), I 48.0 (12.8, 5.3, 13.2, 13.5, 3.2), II 50.8 (14.1, 5.3, 14.0, 14.1, 3.3), III 32.8 (9.8, 3.9, 8.8, 7.7, 2.6), IV 37.1 (11.5, 4.1, 10.6, 10.2, 2.7). Metatarsi III–IV with ventro-distal spine within scopula.

Copulatory organ as in diagnosis ( Figs 6–8 ). Epigynal field as long as wide, with several small muscle attachment points and one pair of slit sensilla very close to the epigynal field. Epigynal plate strongly sclerotised, as long as wide with continuous anterior and incised posterior margin. Copulatory openings situated anteromedially, copulatory ducts running a semi-circle to epigastric furrow with narrow glandular appendages in anterolateral position and oval bends in postero-medial position. Fertilisation ducts arising postero-medially.

Colouration ( Figs 18–19 ). As in male but generally distinctly darker in all parts.

Variation. Males (n=7) with PL 4.8–7.1, OL 6.2–9.2; females (n=11) with PL 5.2–8.8, OL 8.3–13.4. Chelicerae with 4/5 retromarginal teeth (n= 2 females), with 5 retromarginal teeth (n= 1 female). Epigynes may be slightly more elongated, some with more wrinkles close to anterior end of epigynal plate. Some specimens without silt sensilla close to epigynal field, some with slit sensilla barely included in epigynal field.

Natural History. Spiders of this new species live in bamboo forests and seem to occur only on bamboo plants. Rhitymna spiders were recorded on the following bamboo species: Cephalostachyum pergracile Munro ( Thailand), Dendrocalamus strictus (Roxb.) Nees ( Thailand) and Gigantochloa scortechinii Gamble ( Malaysia). Many spiders were found within upright stems in internodes, no matter whether dry or filled with water; several spiders were also found in felled bamboo and in artificially modified internodes made for field experiments. Holes through which spiders enter the internodes were either built by woodpeckers or beetles [ Cerambycidae : exit holes of Abryna regispetri Paiva ; Chrysomeldiae: Lasiochila goryi (Guérin-Méneville) ]. Slits made by woodpeckers had the following measurements: 20 x 5 mm; 10 x 3 mm; 19 x 4.5 mm; 10 x 4 mm; 23 x 5 mm. Round exit holes of the cermabycid beetle Abryna regispetri had about 1 cm in diameter ( Kovac & Yong 1992). The highest internode with a spider inside was found in 16 metres and 35 centimetres. Egg sacs were built inside the bamboo stems. Females attached them to the inner surface and guarded them. They contained 25– 90 eggs. Females were also found with hatched nymphs (n=49) or with hatched nymphs intermixed with unhatched eggs (n=108). One female closed the opening of the bamboo stem from inside with silk. Moreover, moulting took place in internodes, exuviae were found inside the stems. At night time spiders were observed hunting on the bamboo trunk or waiting at the entrance to the internode. Some individuals were observed holding legs out by day or by night, apparently waiting for insects running along the stem ( Fig. 28 ). In the internodes there are only small prey items available like mosquito larvae or small water striders in a low density (all above listed observations by Damir Kovac).

Distribution. Thailand: Mae Hong Son Province, Malaysia: Pahang State ( Fig. 61 ).

Figures

FIGURE 61. Records of Rhitymna species currently known (World Spider Catalog 2019 and works cited therein, records in this paper). Species with larger distribution ranges: stars—R. verruca, light triangles—R. plana, light squares—R. pinangensis. Inset: Sri Lanka.

FIGURES 1–5. Rhitymna gerdmangel spec. nov., holotype male from Mae Hong Son Prov., Thailand. 1–2 Left male palp (1 ventral, 2 retrolateral); 3–4 Tegulum (3 dorsal, 4 retrolateral); 5 Embolus tip, retrolateral. E—embolus, dEA—dorsal embolic apophysis, SP—spermophor, vEA—ventral embolic apopyhsis.

FIGURES 6–11. 6–8 Rhitymna gerdmangel spec. nov., female paratype from Mae Hong Son Prov., Thailand; 9–11 Rhitymna tangi, female from Oudomxai Prov., Laos. 6, 9 Epigyne, ventral; 7, 10 Vulva, dorsal; 8, 11 Schematic course of internal duct system, dorsal. EF—epigynal field, FD—fertilisation duct, FW—first winding of internal duct system, GA—glandular appendage, MP—median plate, OB—oval bend of internal duct system, SS—slit sensillum.

FIGURES 16–27. Rhitymna spp., habitus (16–23, 25–27 in ethanol; 24 alive). 16–19 Rhitymna gerdmangel spec. nov. from Mae Hong Son Prov., Thailand; 20–24 Rhitymna plana, from Tuyen Quang Province, Vietnam; 25–26 Rhitymna tangi, from Oudomxai Prov. Laos; 27 Rhitymna cursor, holotype from Singapore (16–17, 20–21 males, 18–19, 22–27 females).

FIGURES 28–32. Rhitymna spp., habitus, alive. 28 Rhitymna gerdmangel spec. nov., individual of unknown sex, showing two legs hold out of a retreat in a bamboo stalk in Mae Hong Son Province, Thailand, the hole was made by the chrysomelid beetle Lasiochila goryi, and measures 7 by 4 mm (photo by D. Kovac); 29–30 Rhitymna verruca, female from Koh Chang, Thailand; 31–32 Rhitymna pinangensis from Cameron Highlands, Malaysia (31 male, 32 female).