Sobasina Simon, 1898

Prószyński, Jerzy, - & ., 2017, Review of the genus Sobasina (Araneae: Salticidae), Ecologica Montenegrina 15, pp. 53-61 : 54-60

publication ID	https://doi.org/ 10.37828/em.2017.15.8
persistent identifier	https://treatment.plazi.org/id/039F87DE-FFE0-FFA9-0C59-FB5A21A8863B
treatment provided by	Felipe
scientific name	Sobasina Simon, 1898
status

Treatment

Gen. Sobasina Simon, 1898 View in CoL

Type species: Sobasina amoenula Simon, 1898 View in CoL

Definition. Minute jumping spiders (majority of species has body length 3-4 mm, only exceptionally more than 4 mm) characterized by internal structures of epigyne ( Fig. 3 View Figure 3 A-G), unique within Salticidae View in CoL and permitting unequivocal recognition of species when examined under medium power of a compound microscope. Epigyne itself is too small to have much diagnostic value ( Figs 3 View Figure 3 A-C, F, K1-M1). Male palps are relatively homogenous within the genus ( Fig. 5 View Figure 5 ), too small to be examined under dissecting microscope, therefore useless for purpose of species identification but characteristic for the genus. The body shape ( Figs 2 View Figure 2 , 4 View Figure 4 ) is diagnostic, to certain extent, but is too diversified (some species are ant-like, other not) to be used to define genus.

Description. The genus of Sobasina is easily identifiable by general appearance of the body shape (their diversity shown in Figs 2 View Figure 2 , 4 View Figure 4 ), elongated and narrow, with differentiated silhouette of carapace and characteristic microsculpture of body surface, full of microscopic pits and/or sclerotized warts ( Fig. 4 View Figure 4 C-D, G-H). Tegument is light reflecting and in some species form abdominal scutum, those species which have ant-like shape of body may have constrictions additionally marked by white spots or belts ( Fig. 4A, E View Figure 4 ). Genital organs are unique to Sobasina . The legs are thin and rather uniform, leg I are somewhat longer, tibia I may have, sometimes but not always, a ventral mane of black setae, number of spines variable. Body size is minute in most species, in six species its length is 2.07- 3 mm, in several other 3.07-4.27 mm; only females of two species are larger - S. cutleri reach 5.0, S. magna even 7 mm. Classification of these unusual specimens is confirmed by typical internal structure of epigyne (also in case of very unusually shaped S. paradoxa ).

SOURCES. A -Wanless, F. R. (1978d). Bulletin of the British Museum of Natural History (Zool.) 33: 247-248, f 2A-H, B - Zhang J. & Maddison (2015) Zootaxa 3938(1): 71, f. 419-423. All ©copyrights are retained by the original authors and copyright holders, used here by their courtesy.

The most useful character separating species are well visible, sclerotized internal structures of epigyne, unique within the whole family Salticidae , but requiring clearing, staining, mounting in a temporary slide and examination under medium power of a compound microscope (magnification 2-10 x 20-40x). They consist of a long, narrow and entangled (or bent in a complicated way) spermathecae, which opens to the surface of epigyne by indistinct opening and after very short, less sclerotized duct (sometimes not even discernible) pas into slightly broader entrance chamber, which is continued by a narrow but very long "tail" like pipe, which may be differentiated into numerous superficial, sclerotized "beads" (fig. 3B, D) or have internal surface armored with spines or sclerotized rings ( Fig. 3A, C, G, I View Figure 3 ). It should be stressed that understanding such structures require very precise drawings and/or photographs ( Fig. 3 View Figure 3 A-I), drawings simplified or diagrammatic ( Figs 1 View Figure 1 A-B, 3J-M) may be misleading. The superficial sculpture of epigyne is poorly known and of little value ( Fig. 3A, C, F, H, I View Figure 3 ), due to its minute size requiring 200 x magnification of dissecting microscope.

In difference to internal structures of epigyne, the palps are so uniform that are useless for identification of species within the genus Sobasina , their usage is also impracticable because of extremely small dimensions – requiring magnification 200 x (!) of dissecting microscope. Under such power bulbus appears broad oval, spermophor distinct and following margin of bulbus without creating any additional loops ( Fig. 5 View Figure 5 ). The embolus is very short, arising from antero-retrolateral "angle" of bulbus, it is not yet clear how it separates from bulbus. The tibial apophysis is thin and pointed, sometimes slightly waving or inclined, its length is equal to one fourth, rarely half of length of bulbus.

Remarks. 16 cryptic species, known at present, may be hypothesized as the first sample of a diversifying genus in its early phase of island speciation process ( Prószyński, 2010). From our present knowledge, every small Polynesian island tested has its endemic, different species, but on larger islands ( Viti Levu), there are cases of local speciation. The discovery of single species on larger land masses: Peninsula Malaya, Borneo and New Guinea presumably heralds potential existence of many species there. Environments of Sobasina - forest litter (and also moss on higher mountains on Fiji) - are very little studied. All that indicates possibility of existence of more species than heretofore discovered.

Placement of the genus is at present controversial. Simon (1901-1903: 515) knowing only single species proposed a separate group, Sobasineae, for it (together with Fluda Peckham & Peckham, 1892 , rather not related) based on apparently unimportant minor morphological characters, having no apparent phylogenetical importance (parallel to Myrmarachne and other "pluridentate" groups, including Diolenieae). Zhang J. & Maddison (2015: 27) placed Sobasina in euophryines (within their Diolenius clade), claiming that it is "well supported in molecular phylogeny". That placement stands out and their documentation reveals some peculiarities: embolus is slightly different ( Figs 1B View Figure 1 , 5H View Figure 5 ) and drawing of spermatheca is diagrammatized and therefore uncertain ( Fig. 3J View Figure 3 ) – could it be that their specimens are misidentified? The body characters are not exclusive to Sobasina . It is always safer to compare series of species, not single one. Prószyński (2016a, 2017 b: 110) placed Sobasina provisionally in the informal group of genera DIOLENINES (but not included into EUOPHRYINES!) only because of a single criterion - slightly elongate coxa and trochanter I, which in DIOLENINES, however, is strikingly developed. Looking at the unique development of spermathecae and uncertain interpretation of palps, all these classification seems to be unconvincing and Sobasina will probably be placed among genera whose relations cannot be established. An incidental observation of some distant similarities between Sobasina and another unclassifiable genus– Synageles Simon, 1876 , represented by Palaearctic Synageles venator (Lucas, 1836) , may deserve some considerations. There are some distant similarities in palp, spermathecae and habitus, which may indicate some relationships, if confirmed. It seems certain, however, that it cannot be placed within EUOPHRYINES.

Definitions and descriptions of individual species. This paper presents morphological data in a form of precise diagnostic drawings, arranged in a comparative way on plates Fig 3-5 View Figure 3 View Figure 4 View Figure 5 . Such complicated structures cannot be translated into description in words without loss of important details of properties. Owing to facilities provided by the World Spider Catalog, the original descriptions of each species, as well as keys to their identification by somatic characters, can be viewed instantly, or downloaded, by Internet at http://www.wsc.nmbe.ch/. The procedure followed here can be considered a test of future taxonomic descriptions.

SOURCES: A-F - Berry, Beatty & Prószyński (1998) Journal of Arachnology 26: 171-181, f. 67-100, G-H - Prószyński & Deeleman-Reinhold (2013) Arthropoda Selecta 22: 141, f. 116-122, I - Edmunds & Prószyński (2001) Bulletin of the British Arachnological Society 12: 141, f. 9-14, J - Zhang J. & Maddison (2012) Zootaxa 3491: 42, f. 23-204., K-M1 - Wanless, F. R. (1978). Bulletin of the British Museum of Natural History (Zool.) 33: 245-257, f. 1-8. All ©copyrights are retained by the original authors and copyright holders, used here by their courtesy.

SOURCES: A-F - Berry, Beatty & Prószyński (1998) Journal of Arachnology 26: 171-181, f. 67-100, G - Prószyński & Deeleman-Reinhold (2013) Arthropoda Selecta 22: 141, f. 116-122, H - Edmunds & Prószyński (2001) Bulletin of the British Arachnological Society 12: 141, f. 9-14, I-P - Wanless, F. R. (1978). Bulletin of the British Museum of Natural History (Zool.) 33: 245-257, f. 1-8, M - Zhang J. & Maddison, 2012. All ©copyrights are retained by the original authors and copyright holders, used here by their courtesy.

SOURCES: A-F - Berry, Beatty & Prószyński (1998) Journal of Arachnology 26: 171-181, f. 67-100, G - Edmunds & Prószyński (2001) Bulletin of the British Arachnological Society 12: 141, f. 9-14, H - Zhang, J. X. & Maddison, W. P. (2012) Zootaxa 3491: 42, f. 200-204, I -L - Wanless, F. R. (1978). Bulletin of the British Museum of Natural History (Zool.) 33: 245-257, f. 1-8. All ©copyrights are retained by the original authors and copyright holders, used here by their courtesy.

Composition. Type species: Sobasina amoenula Simon, 1898 (Solomon Is.), S. alboclypea Wanless, 1978 (Solomon Is.), S. aspinosa Berry, Beatty & Prószyński, 1998 ( Fiji), S. coriacea Berry, Beatty & Prószyński, 1998 (Caroline Is.), S. cutleri Berry, Beatty & Prószyński, 1998 ( Fiji), S. hutuna Wanless, 1978 (Solomon Is. - Rennell Is.), S. magna Berry, Beatty & Prószyński, 1998 ( Tonga), S. paradoxa Berry, Beatty & Prószyński, 1998 ( Fiji), S. platnicki Prószyński & Deeleman- Reinhold, 2013 (Borneo-Kalimantan), S. platypoda Berry, Beatty & Prószyński, 1998 ( Fiji), S. scutata Wanless, 1978 ( Bismarck Archipelago), S. solomonensis Wanless, 1978 (Solomon Is.), S. sylvatica Edmunds & Prószyński, 2001 ( Malaysia - Peninsula Maya), S. tanna Wanless, 1978 ( Vanuatu), S. wanlessi Zhang J. & Maddison, 2012 (New Guinea), S. yapensis Berry, Beatty & Prószyński, 1998 (Caroline Is.).