Araeoncus hyalinus, Song & Li, 2010

Song, Yanjing & Li, Shuqiang, 2010, The spider genera Araeoncus Simon, 1884 and Diplocephalus Bertkau, 1883 (Arachnida, Araneae, Linyphiidae) of China, Zoosystema 32 (1), pp. 117-137 : 120-125

Araeoncus hyalinus n. sp.

( Figs 1-3 )

TYPE MATERIAL. — Holotype: China, Yunnan Province, Dêqên Zangzu Zizhizhou, Shangri-La County, Bitahai Nature Reserve , 27.83°N, 99.96°E, 15.VI.2006, coll. Y. Song, Z. Cui & J. Xu, ♂ ( MNHN).

Paratypes: same data as for holotype, 2 ♂♂, 10 ♀♀ ( IZCAS) ; 1 ♂, 7 ♀♀ (MNHN). — Yunnan Province, Lijiang Naxizu Zizhixian, Yak Lawn Scenic Area , 27.17°N, 100.25°E, 23.VII.2006, coll. Y. Song, Z. Cui & J. Xu, 1 ♂, 23 ♀♀ ( IZCAS). — Yunnan Province, Lijiang Naxizu Zizhixian, Dragon Spruce Meadow, 27.14°N, 100.23°E, 21.VII.2006, coll. Y. Song, Z. Cui & J. Xu, 1 ♀ ( IZCAS) .

ETYMOLOGY. — Specific name from the Greek adjective hyalinus = transparent, in reference to the slightly sclerotized embolus which appears transparent.

DISTRIBUTION. — Known from Yunnan and Sichuan provinces, China ( Fig. 12 ).

DESCRIPTION

Male

Total length 1.54. Carapace 0.80 long, 0.62 wide, raised into a lobe carrying posterior median eyes, and with cephalic pits within the post-ocular sulci, as well as many moderately long hairs scattered within the ocular area ( Fig. 2A, B ). Clypeus 0.17 high. AME diameter 0.04, ALE 0.06, PME 0.05, PLE 0.05, AME interdistance 0.83 times their diameter, AME-ALE interdistance 1.11 times ALE diameter, PME interdistance 1.38 times their diameter, PME-PLE interdistance 1.38 times PLE diameter. Sternum 0.43 long, 0.44 wide. Coxa IV interdistance 1.11 times their width. Chelicerae with 5 promarginal teeth, 4 retromarginal teeth ( Fig. 2C ). Tibia I 5.85 times longer than deep. Tm I 0.38, Tm IV absent. Dorsal spines on tibia of leg IV: 2-2-1-1; dorsal spine on patella of leg IV: 1-1-1-1. Leg measurements: I: 2.05 (0.61, 0.18, 0.48, 0.43, 0.36); II: 1.87 (0.54, 0.18, 0.43, 0.40, 0.33); III: 1.55 (0.42, 0.18, 0.31, 0.34, 0.29); IV: 2.05 (0.61, 0.18, 0.50, 0.43, 0.33).

Palp: femur nearly twice long as patella.Tibia with one prolateral apophysis, which is composed of 1 thin S-shaped and 1 thick rhombic sclerite ( Fig. 1A ); with 1 prolateral and 2 retrolateral trichobothria ( Fig. 1E ). Paracymbium spiral with terminal part hooked ( Fig. 1D ). Tegulum distal to subtegulum in unexpanded palp ( Fig. 1B ). Protegulum vestigial ( Fig. 1C ). Suprategulum produced into a dentiform marginal apophysis and a bifurcate distal apophysis ( Fig. 2F, G ), as well as a rectangular extension at the base of the distal apophysis ( Fig. 1C ). Embolic division ( Fig. 2D, E ): anterior radical process filmy, pointed obliquely upwards ( Fig. 1B ); mesal tooth long claviform, pointed distally ( Fig. 2D ); posterior radical process transparent, elongate with nearly parallel margins but pointed distally ( Fig. 1D ); embolic membrane long and large, curved to accommodate distal half of the embolus ( Fig. 1B ); tailpiece narrow basally, strongly broadened to be hunched in the middle, narrowed again towards the end ( Fig. 1C ).

Female

Total length 1.67. Carapace 0.65 long, 0.52 wide, similar to male in general appearance and coloration, but without cephalic lobe and sulci. Clypeus 0.09 high. AME diameter 0.04, ALE 0.07, PME 0.06, PLE 0.05, AME interdistance 0.50 times their diameter, AME-ALE separation 0.27 times ALE diameter, PME interdistance 0.58 times their diameter, PME-PLE separation 0.56 times PLE diameter. Sternum 0.41 long, 0.43 wide. Coxa IV interdistance 1.65 times their width. Chelicerae with 5 promarginal teeth, 5 retromarginal teeth. Tibia I 5.00 times longer than deep. Tm I 0.35, Tm IV absent. Dorsal spines on tibia of leg IV: 2-2-1-1; dorsal spine on patella of leg IV: 1-1-1-1. Leg measurements: I: 1.79 (0.53, 0.18, 0.41, 0.35, 0.32); II: 1.75 (0.49, 0.18, 0.38, 0.36, 0.34); III: 1.48 (0.44, 0.18, 0.29, 0.29, 0.28); IV: 1.98 (0.59, 0.18, 0.48, 0.38, 0.34).

Epigynum prominent in lateral view ( Fig. 3C ). Ventral plate with postero-median triangular prolongations separated by a long fissure, anteriorly limited by a rectangular ridge ( Fig. 3B ). Rectangular dorsal plate totally covered by the ventral plate in ventral view ( Fig. 3A ). Spermathecae U-shaped; one arm of the “U” is long oblong while the other is small and almost half long the former ( Fig. 3E ). Copulatory ducts enclosed in a slightly sclerotized capsule, broad and extended with almost parallel margins from copulatory openings, narrowed a bit after turning to the dorsal side, gradually widened again and extended to the ventral side near spermathecae ( Fig. 3D, E ). The path of copulatory duct is shown in Figure 3E . Fertilization ducts short, mesally oriented ( Fig. 3E ).

REMARKS

Araeoncus hyalinus n. sp. and A. longispineus n. sp. have a conformation closely similar to A. humilis (the type species), in having a long coiled and wide, curving ventrally downwards embolus which is unique among the Savignia group genera mentioned by Millidge (1977). Embolus of Dicymbium nigrum (Blackwall, 1834) (the type species; see Roberts 1987: fig.10c), Diastanillus pecuarius ( Simon, 1884) (the type species; see Millidge 1977: fig. 138) and Erigonella hiemalis (Blackwall,1841) (the type species; see Roberts 1987: fig. 36a) is spiral and situated at the anterior end of the embolic division.The form of embolus in Alioranus pauper (Simon, 1881) (the type species; see Millidge 1977: fig. 128), Diplocephalus foraminifer (the type species; see Deltshev 1985: fig. 8) and Glyphesis servulus (Simon, 1881) (the type species; see Millidge 1977: fig. 123) is short and obliquely downwards or upwards. As to Saloca diceros (O. P.-Cambridge, 1871) (the type species; see Millidge 1977: fig. 132) and Savignia frontata Blackwall, 1833 (the type species; see Millidge 1977: fig. 135), their emboli are moderately long, slightly curved, directed backwards or downwards. Besides the form of embolus, both new species are very close to A. humilis in the form of anterior radical process (triangular, pointed obliquely upwards), tailpiece (slightly curved upwards), embolic membrane (running along the embolus),distal suprategular apophysis (extended ventrally and curved more or less upwards) and marginal suprategular apophysis (dentiform). The bisected epigynum, U-shaped spermathecae and path of copulatory ducts of vulva (see Wiehle 1960: fig. 124) is similar too. Furthermore, the chaetotaxy (dorsal spines on tibia of leg IV 2-2-1-1, Tm I 0.35-0.43, Tm IV absent) is also closely similar to A. humilis (dorsal spines on tibia of leg IV 2-2-1-1, Tm I 0.40-0.42,Tm IV absent; see Wiehle 1960).To sum up, both new species have a basically identical conformation with the type species of the genus Araeoncus and hence despite the extra presence of posterior radical process and mesal tooth of embolic division, not present in the other Araeoncus species, both species are placed in the genus Araeoncus .

Araeoncus hyalinus n. sp. and A. longispineus n. sp. share a number of characteristics, including similar body size, body coloration and genital structures, but differ in details. Males can be distinguished by 1) the shape of cephalic lobe, which is much smaller in A. hyalinus n. sp. ( Fig. 2B ) than in A. longispineus n. sp. ( Fig. 5A ); 2) the presence of 3 trichobothria on the palpal tibia in A. hyalinus n. sp. ( Fig. 1A ) versus 2 in A. longispineus n. sp. ( Fig. 4D ); 3) the shape of the palpal prolateral tibial apophysis, which is composed of a S-shaped and a rhombic sclerite in A. hyalinus n. sp. ( Fig. 1E ), but only a long pointed apophysis with membranous base in A. longispineus n. sp. ( Fig. 4D ); 4) the presence of a long thick spine on the cymbial retrobasal process of the palp in A. longispineus n. sp. ( Fig. 4C ), absent in A. hyalinus n. sp. ( Fig. 1D ); 5) the presence of a rectangular extension at the base of the distal suprategular apophysis in A. hyalinus n. sp. ( Fig. 1C ), absent in A. longispineus n. sp. ( Fig. 5A ); 6) the shape of embolus, slightly sclerotized and with almost even dimensions in A. hyalinus n. sp. ( Fig. 2D ), versus highly sclerotized and strongly widened distally in A. longispineus n. sp. ( Fig. 5D ); 7) the relatively short anterior radical process in A. hyalinus n. sp. ( Fig. 1B ), but long and with an extra tooth behind in A. longispineus n. sp. ( Fig. 4B ); and 8) the shape of posterior radical process, which is narrow and almost even in A. hyalinus n. sp. ( Fig. 2D ), wide at the base and strongly narrowed in A. longispineus n. sp. ( Fig.5D ) and the shape of tailpiece of radix, hunched in the middle, blunt distally and slightly upwards in prolateral view in A. hyalinus n. sp. ( Fig. 1C ), but different in A. longispineus n. sp. ( Fig. 4A ).

Females can be further distinguished by the size of the dorsal plate, which is wider than the length of the long arm of the spermatheca in A.hyalinus n. sp. ( Fig. 3A ), but narrower in A. longispineus n. sp. ( Fig. 5F );by the shape of slightly sclerotized capsule where copulatory ducts are embedded, much wider in A. hyalinus n. sp. ( Fig. 3D, E ) than in A. longispineus n. sp. ( Fig. 5F, H ) and by the length of the short arm of the U-shaped spermatheca, which is half the long arm of the spermatheca in A. hyalinus n. sp. ( Fig.3E ), but more than half in A. longispineus n. sp. ( Fig. 5H ).

Furthermore, both new species can be easily diagnosed from other Araeoncus species by the shape of palpal tibial apophyses ( Figs 1E ; 4D ), which are not typical biforked shape as in A. humilis (see Wiehle 1960: fig. 431), by the presence of posterior radical process and mesal tooth of embolic division ( Figs 2E ; 5D ) and by the postero-median triangular prolongations of the bisected epigynum ( Figs 3B ; 5G ).

Specimens of A. hyalinus n. sp. were found under leaf litter or among the roots of moss in mountains above 3000 m. 4 ♂♂ and 40 ♀♀ were measured. Total length varies from 1.53-1.56 in males, 1.36- 1.77 in females. Carapace length is 0.78-0.81 in males, 0.64-0.69 in females; width 0.60-0.62 in males, 0.48-0.56 in females. Coloration of carapace varies from dull-yellow to nut-brown, abdomen light grey to dark grey.

Figures

FIG. 1. — Araeoncus hyalinus n. sp., holotype, ơ cl 0.80 mm (MNHN), Bitahai Nature Reserve: A, tibia of left palp, mesodorsal view; B, left palp, ventral view; C, same, prolateral view (arrow refers to a rectangular extension); D, same, retrolateral view; E, tibia of left palp, dorsal view. Abbreviations: see text. Scale bar: 0.1 mm.

FIG. 2. — Araeoncus hyalinus n. sp., holotype, ơ cl 0.80 mm (MNHN), Bitahai Nature Reserve: A, carapace, dorsal view; B, same, lateral view; C, left chelicera, posterior view; D, embolic division, ventral view; E, same, dorsal view; F, suprategulum, ventral view; G, same, dorsal view. Abbreviations: see text. Scale bars: A, B, 0.2 mm; C-G, 0.1 mm.

FIG. 3. — Araeoncus hyalinus n. sp., paratype, ş cl 0.65 mm (MNHN), Bitahai Nature Reserve: A, epigynum, dorsal view; B, same, ventral view; C, same, lateral view; D, vulva, ventral view; E, same, dorsal view (arrows show the schematic course of internal duct system). Abbreviations: see text. Scale bars: 0.1 mm.

FIG. 12. — Recorded distributions of Araeoncus hyalinus n. sp. (Þ), A. longispineus n. sp. (•), Diplocephalus mirabilis Eskov,1988 (Á) and D. parentalis n. sp. (®) in China.

FIG. 5. — Araeoncus longispineus n. sp., Wuxuhai Lake:A-E, holotype,ơ cl 0.74 mm (MNHN);A, carapace,lateral view;B, suprategulum, ventral view; C, left chelicera, posterior view; D, embolic division, ventral view; E, tailpiece of radix, dorsal view; F-H, paratype, ş cl 0.70 mm (MNHN); F, vulva, dorsal view (arrows show the schematic course of internal duct system); G, epigynum, ventral view; H, vulva, ventral view. Abbreviations: see text. Scale bars: A, 0.2 mm; B-H, 0.1 mm.

FIG. 4. — Araeoncus longispineus n. sp., holotype, ơ cl 0.74 mm (MNHN), Wuxuhai Lake: A, left palp, prolateral view (arrow refers to a tooth behind the anterior radical process); B, same, ventral view; C, same, retrolateral view; D, tibia of left palp, dorsal view. Abbreviations: see text. Scale bars: 0.1 mm.