Storenosoma Hogg, 1900

Milledge, G. A., 2011, A Revision of Storenosoma Hogg and Description of a New Genus, Oztira (Araneae: Amaurobiidae), Records of the Australian Museum 63 (1), pp. 1-32 : 13-14

Genus Storenosoma Hogg

Storenosoma Hogg, 1900: 95 . Type species: Storenosoma hoggi (Roewer, 1942) .

Diagnosis. Storenosoma can be distinguished from other amaurobiids except Otira , Oztira and Pakeha by the possession of paired stridulatory spines on the trochanter of the male palp ( Fig. 3c ) and associated stridulatory field on prolateral face of the coxa of leg 1 ( Fig. 3d ); from Otira and Pakeha by both eye rows strongly procurved, PLE and to a lesser extent PME enlarged ( Fig. 1a–c ) and tarsal organ capsulate or, if peg-like, being situated proximal to trichobothria ( Figs 7–8 ); from Oztira by metatarsus on leg 1 of male being cylindrical ( Fig. 4e ).

Description. Medium sized (CL 3.0–5.6), ecribellate, ground dwelling spiders. Cephalothorax, legs and chelicerae golden to orange brown. Cephalothorax often with darker dorsal markings in radial pattern around fovea, region around eyes very dark, chilum absent. Both eye rows strongly procurved, posterior eyes, particularly PLE, enlarged. ALE with canoe shaped tapetum, PME with flocculent reflective layer and PLE with diffuse reflective layer (pers obs). Chelicera vertical with prominent retrobasal boss, two retromarginal and two promarginal teeth, promargin also with row of minute teeth distal and slightly posterior to large teeth ( Fig. 3a ). Paturon with numerous sensory hairs toward promargin of fang groove and a particularly elongate hair at fang base, single elongate hair at fang base on retromargin. Maxillae slightly longer than wide, lateral margins convex, with strong linear serrula. Labium about as wide as long, with notched apex. Paired stridulatory spines on the trochanter of the male palp and associated stridulatory field on prolateral face of coxa 1. Cymbium of male palp with trichobothria ( Fig. 3b ) and retrolateral bulge associated with basal depression ( Figs 2c,d ). Complex RTA. Stout, blunt to pointy tipped embolus, membranous conductor, complex MA often with proximal or prolateral processes, TA well developed to absent. Legs with dark banding and blotches. Legs 4123. Trochanters of legs 3–4 shallowly notched. Tibia and metatarsi of legs strongly spinose, tarsal organ capsulate or rod like, trichobothrial hoods longitudinally striated, preening combs on metatarsi 2–4 ( Fig. 3e ). Abdomen grey brown, flecked with darker and lighter spots, sometimes with paired, dark coloured chevrons in distal half. Epigynum with lateral teeth and distinctly sclerotized gonopore openings, spermathecae and copulatory ducts simple.

Remarks. The species are all quite similar in appearance and can only be confidently separated on the basis of genital morphology. Only male characters are used in the key as females are not known for all species, the genitalia of the known species are fairly conservative and, similar to Oztira , the epigyna of most females collected are plugged with a hard, dark resinous substance which obscures external and to some extent internal characters, making specific identification difficult. This substance is extremely tough and is deposited both internally and externally on the epigynum. The author was unable to remove it mechanically or chemically using bleach solution or potassium hydroxide solution. This plug is most likely produced by the male in a similar fashion to that of Amaurobius C.L. Koch 1837 ( Suhm et al., 1996) and also noted by Davies (2003) in Tangana Davies, 2003 . Forster & Wilton (1973) also noted mating plugs in Pakeha minima Forster & Wilton, 1973 . Whether these plugs completely preclude further matings is debatable. Eberhard (1985) argues that female mate selection is the driving force behind interspecific differences in male genitalia and for it to operate multiple matings must occur. However, as in Amaurobius , the mating plug in Storenosoma is very tough and it is difficult to envisage it being removed by mechanical means. It seems likely that the “lateral epigynal protuberances” described by Davies (1998) for Tasmarubrius Davies, 1998 are similar mating plugs. Davies (2002) also mentions plugs in the epigyna of some specimens of Tasmabrochus cranstoni Davies, 2002 . Also notable is the variation in the tarsal organ within this genus. Most species have the tarsal organ capsulate and distal to the trichobothria. In three species it is situated between the first and second trichobothrium and in one of these it is raised somewhat. One species has a rod like tarsal organ situated proximal to the trichobothria, similar to Oztira .

Included species. Storenosoma altum Davies , S. bifidum n.sp., S. bondi n.sp., S. forsteri n.sp., S. grayi n.sp., S. hoggi (Roewer) , S. grossum n.sp., S. picadilly n.sp., S. smithae n.sp., S. supernum Davies , S. tasmaniensis n.sp., S. terraneum Davies and S. victoria n.sp.

Figures

Fig. 3. Storenosoma hoggi. (a) chelicera (arrow indicates small teeth row) (K4097), (b) cymbial trichobothria (indicated by arrows) (K4042), (c) stridulatory spurs on male palpal trochanter (K4042), (d) stridulatory field on prolateral face of male coxa 1 (K4042), (e) tarsal preening comb (K4097).

Fig. 1. Cephalothorax and eye pattern.(a) Oztira affinis,(b) Oztira kroombit, (c) Storenosoma hoggi, (d) Otira satura, (e) Pakeha protecta.

Fig. 7. Tarsal organ and trichobothria. (a, e–f) Storenosoma grayi (KS69899): (a) tarsus leg I, (e) tarsal organ and trichobothrial base, (f) tarsal organ ventral. (b, g–h) Storenosoma altum (KS37226): (b) tarsus leg I, (g) tarsal organ and trichobothrial base, (h) tarsal organ lateral. (c, i) Storenosoma hoggi (K4097): (c) tarsus leg I, (i) tarsal organ and trichobothrial base. (d, j) Storenosoma bondi (KS18071): (d) tarsus leg I, (j) tarsal organ and trichobothrial base.

Fig. 8. Tarsal organ and trichobothria. (a, e) Storenosoma forsteri (KS52409): (a) tarsus leg I, (e) tarsal organ and trichobothrial base. (b, f) Storenosoma smithae (ANIC, NSW, Mt Clarke, Mar 2004): (b) tarsus leg I, (f) tarsal organ and trichobothrial base. (c, g) Storenosoma tasmaniensis (TMG147): (c) tarsus leg I, (g) tarsal organ and trichobothrial base. (d, h) Storenosoma victoria (K4277): (d) tarsus leg I, (h) tarsal organ and trichobothrial base.

Fig. 4. Forelegs. (a–c) Oztira aquilonaria male (S1371): (a) left foreleg tibia and tarsal segments, (b) ventral scopula on metatarsus, (c) tarsal claws. (d) Oztira affinis male (KS101138), left foreleg tibia and tarsal segments. (e) Storenosoma altum female (KS37226), right foreleg tibia and tarsal segments.

Fig. 2. Storenosoma hoggi (KS71594), male palp (arrows indicate basal expansion of embolus). (a) prolateral, (b) ventral, (c) retrolateral, (d) dorsal.