Tropizodium, Jocqué, Rudy & Churchill, Tracey B., 2005

Jocqué, Rudy & Churchill, Tracey B., 2005, On the new genus Tropizodium (Araneae: Zodariidae), representing the femoral organ clade in Australia and the Pacific, Zootaxa 944, pp. 1-10 : 3-4

Tropizodium n. gen.

Diagnosis: Members of the genus are recognised by the following combination of characters: tiny spiders with minute secondary eyes, the PME close to the AME; a small intercheliceral triangle; not more than 1 dorsal spine on femora which are densely set with flattened incised setae; epigyne very simple without clearly defined entrance ducts; males without indurated opisthosomal dorsum; embolus short and straight.

Type species: Tropizodium peregrinum n. sp. (♂Ψ)

Other species included: Tropizodium molokai n. sp. (♂Ψ), Zodarion trispinosum Suman (♂Ψ)

Etymology: This generic name is a combination of Zodarium and tropical. Gender is neuter.

Description: Small spiders (1.5–3.6 total length). Carapace and other parts of prosoma almost white to pale yellow. Legs uniform pale yellowish. Opisthosoma: uniform dark sepia mottling; sides and venter pale; males without indurated opisthosomal tegument. Carapace ( Fig. 6 ): smooth, oval; widest between coxae II and III; narrowed in front to less than 0.71 times maximum width in females, to 0.65 maximum width in males (cephalic width measured on posterior tangent of PME).

Eyes ( Figs. 6–8 ) in two rows: posterior one strongly procurved; anterior row only slightly so. AME large, dark, circular; other eyes small and light; lateral eyes rounded, PME oval. AME their radius apart and slightly less from ALE; PME 4 to 5 times their diameter apart and about 1 diameter from PLE. MOQ slightly wider than long and anterior width almost equal to posterior width. Clypeus ( Figs. 7, 9 ) slightly convex and about as high as 1.5 times the diameter of an AME.

Chilum absent. Chelicerae ( Figs. 7–8 ): ventrally fused at slightly less than halfway along their length; strong setae on dorsal side; distal cusp bearing a tooth; intercheliceral triangle small. Fang shorter than wide at the base. Endites strongly convergent, roughly rectangular. Labium triangular with narrowed base. Sternum: slightly longer than wide; basically triangular with rounded sides; provided with triangular extensions fitting in coxal concavities.

Legs slender. Formula 4123. Spination: Femora I–III with 1 dorsal spine. Flattened incised hairs dense on femora, less dense on remainder of legs. Trichobothria in two rows on tibia, in one row on metatarsus and tarsus. Femoral organ ( Fig. 1 ) with two barbed hairs, poorly developed. Opisthosoma oval and without dorsal scutum in male. Tracheal spiracle: narrow, 0.2–0.4 times width of opisthosoma; straight; anterior margin slightly sclerotized and with a row of thin setae. Spinnerets: female with six, male with two; anterior pair long, conical, 2­segmented on a broad sockle; posterior pairs small. Colulus absent. Male palp ( Figs. 4–5 , 10–11 , 14–15 , 18–19 ): RTA well developed, sometimes reaching distal tip of cymbium, with modified prolateral setae; median apophysis variable in size and shape; embolus short, almost straight. Epigyne ( Figs. 12–13 , 16–17 , 20 ): extremely simple, a smooth indented plate; copulation ducts very short; spermathecae globular or ovoid, far apart. Female palpal tarsus ( Fig. 3 ): conical; finely toothed claw turned inward over almost 90° so that the teeth are pointing inward; with a few prolateral modified setae.

Distribution: So far known from the Hawaiïan Islands and northern Australia. The description of Zodarion luzonicum Simon, 1893 based on juveniles from the Philippines ( Simon 1893a, b) may represent a species belonging to Tropizodium .

Affinities: This genus doubtlessly belongs in the “femoral organ” clade and more precisely, in the group of genera containing Zodarium Walckenaer and Zodariellum Andreeva & Tyschenko. In the cladogram presented by Jocqué (1991) this clade is poorly resolved and urgently needs a thorough revision and reanalysis. Tropizodium shares with Zodarion the cheliceral triangle, the legs covered with flattened indented shiny hairs and the small femoral organs. It differs from Zodarion by the position of the PME being closer to the AME and by the much smaller intercheliceral triangle.

Figures

FIGURES 6 – 9. Tropizodium peregrinum n. gen., n. sp. 6. Female, habitus; 7. Female, lateral view; 8. Prosoma, ventral view; 9. Prosoma, frontal view. (scale lines: 0.5 mm)

FIGURES 1 – 5. Tropizodium peregrinum n. gen., n. sp. Scanning electron micrographs. 1. femoral organ on leg II of female, dorsolateral view; 2. chelicerae, ventral view; 3. Female right palpal tarsus, dorsal view showing distal toothed claw turned inwards over 45 ° and modified setae; 4. male right palp, retrolateral view; 5. Median apophysis, prolateral view.

FIGURES 10 – 13. Tropizodium peregrinum n. gen., n. sp. 10. Male palp, lateral view; 11. Male palp, ventral view; 12. Epigyne, ventral view; 13. Epigyne, cleared, dorsal view. (scale lines: 0.1 mm)

FIGURES 14 – 17. Tropizodium molokai. n. gen., n. sp. 14. Male palp, lateral view; 15. Male palp, ventral view; 16. Epigyne, ventral view; 17. Epigyne, cleared, dorsal view. (scale lines: 0.1 mm)

FIGURES 18 – 20. Tropizodium trispinosum (Suman) 18. Male palp, lateral view; 19. Male palp, ventral view; 20. Epigyne, ventral view. (scale lines: 0.1 mm)