Cavisternum, Baehr & Harvey & Smith, 2010

Baehr, Barbara C., Harvey, Mark S. & Smith, Helen M., 2010, The Goblin Spiders of the New Endemic Australian Genus Cavisternum (Araneae: Oonopidae), American Museum Novitates 3684, pp. 1-40 : 4-6

Cavisternum , new genus

TYPE SPECIES: Cavisternum clavatum , new species.

DIAGNOSIS: Males of this genus can easily be recognized and separated from all other genera by the concave sternum covered with clavate setae (figs. 7–25, 33–35, 106, 108, 147, 150), and the elongated fangs with a broadened tip (figs. 39–41, 107, 148). It is currently not possible to distinguish female specimens of Cavisternum from other genera.

ETYMOLOGY: The generic name is from Latin and refers to the concave sternum, which is present in males of all Cavisternum species. The gender is neuter.

DESCRIPTION: Small spiders, total length of males 0.98–1.25; females, 1.12–1.33.

Carapace not elevated (figs. 27–31), ovoid, anteriorly narrowed to less than 0.49X its maximum width, with rounded posterolateral corners, lateral margin rebordered, surface smooth. Clypeus straight in front view and vertical in lateral view, high, ALE separated from edge of carapace by more than their radius (figs. 28, 32). Clypeus and nonmarginal pars cephalica covered with dark needlelike setae. Chilum absent. Six eyes, well developed, ALE largest, circular, PME oval, PLE circular, posterior eye row straight from above, procurved in front view (figs. 26, 28, 103, 105, 144, 146). ALE–ALE separated by less than ALE radius, ALE–PLE separated by less than ALE radius, PME–PME touching throughout most of their length, PLE–PME touching.

Sternum as long as wide, unmodified in females (fig. 29), but in males with teardropshaped median concavity of variable extent and position and partly to fully covered with field of clavate setae (figs. 7–25, 33–35).

Chelicerae, endites, and labium pale orange. Cheliceral teeth absent, cheliceral fangs small and medially directed in females (figs. 29, 36– 38), in males fang directed posteriorly, elongat- ed, tip widened with ridges and flanges or spikes, bent posterolaterally (figs. 39–41). Cheliceral setae dark, needlelike, evenly scattered. Labium rectangular, not fused to sternum, with anterior margin indented at middle, with three setae. Endites not excavated distally, with serrula present in single row (fig. 39), anteromedian tip with one strong, toothlike projection in males, posteromedian part unmodified (figs. 39, 40).

Abdomen ovoid, dorsal scutum weakly sclerotized, covering full length of abdomen, pale orange, without color pattern, top and sides smooth, not fused to epigastric scutum (fig. 42). Epigastric scutum weakly sclerotized, surrounding pedicel, ventrally plain, weakly or strongly protruding; book lung covers large, ovoid, without setae; pedicel tube short, ribbed. Epigastric furrow separates epigastric scutum from postepigastric scutum (figs. 82–83). Postepigastric scutum weakly sclerotized, long, almost rectangular, covering about L of abdominal length, fused to epigastric scutum in males, with long posteriorly directed lateral apodemes. Spinneret scutum present as an incomplete ring. Colulus represented by two setae. ALS and PLS with two major ampullate gland spigots, PMS with just one minor ampullate gland spigot in both sexes (figs. 73–76). Sperm pore oval, situated in front of anterior spiracles, with or without protruding extension (figs. 4–6, 42, 43).

Legs yellow, not darkened, femur IV not thickened, same size as femora I–III. Leg spines absent; tibiae I–IV with three dorsal trichobothria (figs. 44–48), metatarsi I–IV with one dorsal trichobothrium near the distal end, trichobothrial base rounded (figs. 49–52, 63– 66), tarsi I–IV with drop-shaped tarsal organ and 1–2 sensillae visible in males, 3 in females (figs. 53–57, 67–70). Tarsal claws with 4 smaller teeth at inner margin and 4 larger teeth at lateral margin in males (figs. 59–62, 72) in females the inner 4 teeth are larger (fig. 58, 71).

Male palp normal, not strongly sclerotized, proximal segments, cymbium, and bulb yellow, embolus dark. Palpal trochanter normal, femur more than twice as long as trochanter, attached to basal patella, patella about as long as femur, tibia shorter than patella. Cymbium ovoid in dorsal view, completely fused with bulb without visible seam; bulb tapering apically, bearing a long, medially bent embolus (figs. 77–81).

Female palp without claw, epigastric area with unpaired copulatory duct between tracheal spiracles which is connected by groove and epigastric furrow (figs. 82–83).

REMARKS: The genus Cavisternum includes 19 new species. The type species is treated first, followed by the other species in alphabetical order. The species descriptions mention only the differences from this generic description.

KEY TO SPECIES OF CAVISTERNUM

(females not known for C. bagleyae , C.

barthorum, C. carae , C. gatangel , C. hughesi , C. maxmoormanni , C. noelashepherdae and C. waldockae )

1. Males........................... 2

– Females......................... 20

2. Abdomen, epigastric scutum unmodified (fig. 5).......................... 14

– Abdomen, epigastric scutum protruding (figs. 4, 6)........................ 3

3. Abdomen, epigastric scutum strongly protruding (fig. 4)........................ 4

– Abdomen, epigastric scutum slightly protruding (fig. 6)........................ 9

4. Concave field of clavate setae extends the whole length of the sternum, fangs undulate (fig. 21).................. C. mayorum

– Concave field of clavate setae extends L length of sternum or less, fangs not undulate.... 5

5. Concave field of clavate setae shallow, extends less than J length of sternum (fig. 20)......................... C. maxmoormanni

– Concave field of clavate setae drop shaped extends at least K length of sternum..... 6

6. Concave field of clavate setae drop shaped, length about L of sternum (fig. 7)................................. C. clavatum

– Concave field of clavate setae drop shaped, length about K of sternum (figs. 12, 13, 14)...... 7

7. Tip of embolus bifurcate (figs. 98–100).............................. C. digweedi

– Tip of embolus not bifurcate but with basal projection (figs. 90, 95)............... 8

8. Basal embolar projection large, rounded (figs. 90–92)............... C. bertmaini

– Basal embolar projection tiny with sharp tip (figs. 95–97).................. C. carae

9. Concave field of clavate setae shallow extends less than J length of sternum, fang tip widened (fig. 9)............... C. michaelbellomoi

– Concave field of clavate setae extends at least K length of sternum, fang tip not widened.... ................................. 10

10. Concave field of clavate setae extends the whole length of sternum (figs. 18, 22, 25)...... 11

– Concave field of clavate setae about K length of sternum (figs. 17, 23)............. 13

11. Anterior margin of sternal field with a row of stiff setae, fangs reduced (fig. 22)............................. C. noelashepherdae

– Anterior margin of sternal field without a row of stiff setae, fangs long............. 12

12. Fangs aligned in a V shape, embolus tip bent retrolaterally (fig. 173)....... C. waldockae

– Fangs crossing, embolus tip bent prolaterally (fig. 130)................... C. hughesi

13. Palpal bulb with conical projection at about O length of bulb, embolus short with two additional long prongs (figs. 163–165)............................ C. rochesterae

– Palpal bulb with conical projection absent, embolus long, without two projections (figs. 123–125)............. C. heywoodi

14. Embolus with long sharp basal projection (figs. 131–135)............... C. ledereri

– Embolus without such projection....... 15

15. Sternum, anterior edge of clavate field rounded (figs. 8, 11, 24).................... 16

– Anterior edge of clavate field angular (figs. 10, 15, 16).......................... 18

16. Fangs relatively short, not reaching tip of labium (fig. 11)............ C. barthorum

– Fangs long, reaching at least tip of labium (figs. 8, 24)....................... 17

17. Fangs cross, tips bent medially (fig. 8) C. ewani

– Fangs crossed, tips bent laterally (fig. 24)........................... C. toadshow

18. Bare median band half as long as clavate field (fig. 16)................... C. gatangel

– Bare median band about L as long as clavate field (figs. 10, 15).................. 19

19. Fangs long, straight, crossed, reaching endites (fig. 15)..................... C. foxae

– Fangs short, straight, not reaching endites (fig. 10)................... C. bagleyae

20. Epigastric area with copulatory duct not reaching tracheal groove (figs. 82, 101, 134, 164, 169)........................ 21

– Epigastric area with copulatory duct reaching tracheal groove (figs. 113, 118, 126, 142, 156)............................ 25

21. Epigastric area with wide semicircular rim (figs. 101, 164).................... 22

– Epigastric area without semicircular rim... 23

22. Semicircular rim thick, leading to narrow copulatory duct (figs. 101, 102).. C. digweedi

– Semicircular rim thin, copulatory duct triangular, anteriorly widened (figs. 164, 165)............................ C. rochesterae

23. Epigastric area with a dark rectangular field between epigastric fold and tracheal groove (figs. 169, 170)............. C. toadshow

– Epigastric area with a dark oval or elliptical field between epigastric fold and tracheal groove (figs. 82, 134)............... 24

24. Epigastric area with a longitudinal dark oval field between epigastric fold and tracheal groove (figs. 82, 83).......... C. clavatum

– Epigastric area with a dark broadly spatulate field between epigastric fold and tracheal groove (figs. 134, 135).......... C. ledereri

25. Posterior end of copulatory duct at level of tracheal groove (figs. 93, 113, 156)...... 26

– Posterior end of copulatory duct far beyond tracheal groove (figs. 118, 126, 142)..... 28

26. Epigastric area with wide, V-shaped dark field (figs. 156, 157)......... C. michaelbellomoi

– Epigastric area without wide, V-shaped dark field (fig. 113)..................... 27

27. Epigastric area with wide elliptical opening just behind epigastric fold, posterior end of copulatory duct just behind tracheal groove (figs. 113, 114)................ C. ewani

– Epigastric area without elliptical opening, posteriorend of copulatory duct on level of tracheal groove (figs. 93, 94)..... C. bertmaini

28. Copulatory duct long and not divided into three parts (figs. 118, 142)............ 29

– Copulatory duct short and divided into three parts (figs. 126, 127)......... C. heywoodi

29. Copulatory duct long and narrow, about 3X longer than wide (figs. 118, 119).... C. foxae

– Copulatory duct long but broader, about 2X longer than wide (figs. 142, 143)................................. C. mayorum