Ossinissa, Dimitrov, Dimitar & Ribera, Carles, 2005

Dimitrov, Dimitar & Ribera, Carles, 2005, Description of Ossinissa, a new pholcid genus from the Canary Islands (Araneae: Pholcidae), Zootaxa 982, pp. 1-13 : 3-8

Ossinissa new genus

Type species. — Spermophorides justoi Wunderlich 1992

Etymology. — The generic name honors Ossinissa , the last king of El Hierro Island before its conquest by the Norman Jean de Bethencourt at the beginning of the 15th century. Gender is masculine.

Diagnosis. — The opisthosoma is cylindrical in males and oval in females ( Fig. 25 ). Prosoma and habitus as in Figs. 21–22. Ocular area elevated and placed close to the center of the prosoma. Distinguished from closely related genera ( Pholcus , Micropholcus , Leptopholcus and Spermophora ) by the shape of the prosoma (Fig. 21) and the morphology of the procursus with characteristic dorso­retrolateral apophysis and concave shape. A useful character for identification purposes is the shape of the tarsal organ ( Figs. 6, 13 ), which in Ossinissa new genus is flat (sensu Huber 2000, 2003), while in all closely related genera it is capsulated. Although the small size and the globular shape of the female opisthosoma may lead to some confusion with Spermophora or Spermophorides , Ossinissa new genus can be easily distinguished by the presence of a well­developed uncus ( Figs. 1, 5 , 14, 20), the structure of the procursus (Fig. 24) and the presence of eight eyes. Additionally, the absence of the “bump” of the epigynum in Ossinissa new genus clearly separates this genus from Spermophorides , and the lack of pockets in the vulva is a useful trait when differentiating from Spermophora .

The most important characters that distinguish Ossinissa new genus from small­sized Pholcus species are: the cavity of the procursus; the dorso­retrolateral apophysis of the procursus, and the shape of the tarsal organ. The absence of a heavily sclerotized structure around the pore plates in the female genitalia of Ossinissa new genus is also a good diagnostic character.

Description. — Ochre­yellowish pholcids. Total body length in males slightly smaller than in females. Prosoma shape as in Fig. 21. The ocular area moderately elevated and situated roughly in the center of the prosoma. Eight eyes. In the type species, eyes are reduced, especially the AME. The arrangements of the eyes as in most eight­eyed pholcids; ALE, PME and PLE grouped in two triads placed on the lateral margins of the ocular area. Lateral triads are placed on two short cylindrical outgrowths. AME situated between the triads on the frontal side of the ocular area. Ocular area surrounded by a slight depression of the prosoma. Male chelicerae ( Figs. 3 , 17) with distal apophyses ( Fig. 9 ) carrying modified hairs (sensu Huber 2000) and proximolateral apophyses. In females, chelicerae bear no apophyses. Male palpal trochanter with retrolateral process, femur cylindrical with ventral bulge. Procursus robust and narrower at the base (Fig. 24), with a cavity open toward the bulb. Distally, procursus with well developed dorso­retrolateral apophysis. Genital bulb with three projections: uncus (Fig. 20), appendix and embolus. Embolus with membranous structure. Leg formula 1423. Legs and body covered with short hairs. Opisthosoma almost cylindrical in males and globular in females. Spinnerets ( Figs. 26–29 ) situated ventrally close to the end of the opisthosoma. Epigynum elevated. Vulva with heavily sclerotized valve ridge.

FIGURES 14–24. Ossinissa justoi new combination, male (14–15, 17, 20, 22, 24), female (16, 18– 19, 21, 23). 14. Male palp, retrolateral; 15. Male palp, prolateral; 16. Vulva, dorsal; 17. Male chelicerae, frontal; 18. Female prosoma, lateral; 19. Epigynum, ventral; 20. Uncus, retrolateral; 21. Female body, lateral; 22. Male body, dorsal; 23. Epigynum, lateral; 24. Procursus, dorsal. Scale bars: 0.2 mm.

Generic relationships. — This genus shares several synapomorphies with the members of the genus Pholcus . The most important of these is the presence of a well­developed uncus. Similarities can be observed in the general structure of the male palp (the shape of femur, tibia and trochanter). The distribution of the eyes is also similar to that in Pholcus . However, despite these similarities, the structure of the procursus in Ossinissa new genus differs greatly; the tarsal organ is flat while that in Pholcus is capsulated; the chelicerae do not have frontal prominences and the morphology of the female vulva is distinct.

Although O. justoi was placed initially in Spermophorides , it does not share any character with the members of this genus except for the globular shape of the female opisthosoma.

Relationships were examined by means of a cladistic analysis. The data matrix used for the analysis is listed in Appendix 1. The matrix was based on Huber 2003 but was modified as follows:

1 Several taxa were deleted, mainly New World genera and ninetines, which would not have contributed to the determination of Ossinissa new genus and its close relatives. 2 O. justoi and some Pholcus species from the Canary Islands were added ( P. fuerteventurensis , P. ornatus and P. gomerae ).

3 One character was added: 60 – shape of the opisthosoma; 0 – cylindrical, 1 – elevated (the opisthosoma does not present regular height). When the opisthosoma was elevated in one of the two sexes, the species was coded as 1. (Note that the total number of characters is 61 but they are numbered starting from 0).

Using a previously published matrix from which several non­related taxa were deleted resulted in a high number of non­informative characters.

Running NONA with hold 10000 and mult*1000 gave as a result 81 most parsimonious trees with 94 steps. The strict consensus of these trees is given in Appendix II. In addition, the stability of the clades was estimated by calculating the bootstrap and jackknife support using NONA. In all trees generated by the analysis, Ossinissa new genus is placed in a clade formed by Micropholcus , Pholcus and Leptopholcus . In this group Micropholcus occupies in most of the cases a basal position, and Ossinissa new genus is recognized as the closest relative of Pholcus . In all cladograms Pholcus appears to be paraphyletic with respect to Leptopholcus and this is supported by both bootstrap and jackknife. This could be one more evidence for the possible synonymy of Pholcus and Leptopholcus ( Brignoli, 1980; Huber, 2001).

The application of implied weighting with Pee­Wee (algorithm that resolves character conflict in favor of characters that present less homoplasy) with K from 1–6 produced the same result as NONA.

The placement of Ossinissa new genus outside Pholcus in all of the analyses, and the fact that the clade Pholcus + Leptopholcus appears in all cladograms and is supported by bootstrap and jackknife, upholds the existence of Ossinissa new genus as separate genus. Although these results suggest that Leptopholcus is a synonym of Pholcus , this would need further investigation.

In summary, we conclude that Ossinissa new genus is closely related with the genera in the Pholcus group: Pholcus , Micropholcus and Leptopholcus .

Distribution. – The distribution of this genus is restricted. The Cueva de Don Justo and the Cueva de los Pocitos on El Hierro Island are the only two locations where it has ever been reported.

Included species. – Currently, this genus includes only one species, Ossinissa justoi new combination.

Figures

FIGURES 25 – 29. Ossinissa justoi new combination, female. 25. Opisthosoma, lateral; 26. Anterior lateral spinnerets, ventral; 27. Ocular area, dorsal; 28. Spinnerets, ventral; 29. Posterior median spinnerets, ventral. Scale bars: 25: 500 µm; 26: 20 µm; 27: 100 µm; 29: 10 µm; 28: 50 µm.

FIGURES 1 – 13. Ossinissa justoi new combination, male. 1. Uncus, retrolateral; 2. Apex of the procursus, retrolateral; 3. Chelicerae, frontal; 4. Procursus, retrolateral; 5. Uncus, dorso­retrolateral; 6. Tarsal organ, lateral; 7. Palp, dorso­retrolateral; 8. Palp with procursus, dorsal; 9. Distal apophyses of the chelicerae, fronto­lateral; 10. Ocular area, frontal; 11. Procursus, ventral; 12. Male palp, prolateral; 13. Tarsal organ, fronto­lateral. Scale bars: 1 – 5, 10 – 11: 100 µm; 7 – 8, 12: 200 µm; 4: 50 µm; 13: 40 µm; 6: 20 µm; 9: 10 µm.