Stahnkeus Soleglad et Fet, 2006

Soleglad, Michael E. & Fet, Victor, 2006, Contributions to scorpion systematics. II. Stahnkeini, a new tribe in scorpion family Vaejovidae (Scorpiones: Chactoidea), Euscorpius 40 (40), pp. 1-32 : 29-30

Stahnkeus Soleglad et Fet , gen. nov.

Type species. Vaejovis harbisoni Williams, 1970 [= Stahnkeus harbisoni (Williams, 1970) ].

Diagnosis. Closely related to sister genus Serradigitus , from which it can be distinguished by the following synapomorphic (derived) character: pedipalp chelal fingers exhibit an irregular number of inner (IAD) accessory denticles, the number increasing during ontogenetic development; number of ID + IAD is species-dependent and ranges from 6 to 18 and from 8 to 20 for the fixed and movable fingers, respectively. Otherwise, genus Stahnkeus exhibits characters of the tribe.

Etymology. This genus is named after Herbert L. Stahnke for his contributions to scorpion systematics and for being the first to describe a species of Serradigitus in 1940 and establishing the genus Serradigitus in 1974.

Distribution. Mexico (Baja California , northern Sonora) and United States (Arizona, California ). See map in Fig. 47 .

Species list. The following five species comprise this genus; general locality data based on specimens examined, Williams (1970a, 1980, in part); Soleglad (1972), Berke (1987, in part), Sissom & Stockwell (1991), Sissom (2000).

S. allredi (Sissom et Stockwell, 1991) , comb. nov. Southern Arizona, USA; northern Sonora, Mexico. S. deserticola (Williams, 1970) , comb. nov. Death Valley, California , USA ( Figs. 32 , 42).

S. harbisoni (Williams, 1970) , comb. nov. Central Baja California , Mexico ( Figs. 30 , 41).

S. polisi (Sissom et Stockwell, 1991) , comb. nov. Sonora, Mexico.

S. subtilimanus ( Soleglad, 1972) , comb. nov. Southern California , southwestern Arizona, USA; northern Baja California , northern Sonora, Mexico (Figs. 6, 7, 15, 16, 31, 43–45, 46).

Discussion. In comparison with the broader distribution of Serradigitus ( Fig. 46 ), the genus Stahnkeus forms roughly a contiguous “horseshoe” pattern around the Sea of Cortez, extending northward to Death Valley, California and southward to central Baja California state in the west and Sonora, Mexico, in the east. In the map ( Fig. 47 ) two northern localities originally reported for species S. harbisoni by Williams (1980) have been changed to S. subtilimanus , this based on the somewhat disjunct ranges of the specialized microhabitat required by this genus (i.e., they are lithophilic). In addition, the report of S. harbisoni from extreme southern Baja California Sur, Isla Cerralvo ( Williams, 1980: 103), is unlikely in our opinion, therefore we consider this a locality misidentification.

The five species of Stahnkeus can be separated by the characters provided in Table 7. Genus Stahnkeus contains the largest species in tribe Stahnkeini , S. harbisoni , which reaches lengths of 50 mm. Three species, S. deserticola , S. subtilimanus and S. harbisoni , are closely related, their disjunct distribution forming a north to south pattern from Death Valley, California through the Colorado Desert in southern California , to central-east Baja California state (see map in Fig. 47 ). All adults of these three species share an attractive yellow-orange coloration of the metasoma, legs and pedipalps with dark mahogany highlights on the pedipalp and metasomal carinae; dusky patterns of the carapace are absent in these species (see Fig. 48 of an adult male S. subtilimanus ). As typical of large species of tribe Stahnkeini , the trichobothrial series ib–it in these three species is located roughly midfinger ( Tab. 5). The other two species, S. allredi and S. polisi from southern Arizona, USA, and Sonora, Mexico, are smaller in size, exhibit dusky patterns on their carapaces, and trichobothria ib–it are located more proximally on the fixed finger (after Sissom & Stockwell, 1991).

Figures

Figure 46: Reported distribution of tribe Stahnkeini. • = Serradigitus (species identified); O = Stahnkeus (see Map in Fig. 47 for species identifications). Localities based on specimens examined and from the following sources: Stahnke (1940a, 1940b), Gertsch & Allred (1965), Williams (1968, 1970a, 1970b, 1980), Hjelle (1972), Soleglad (1972, 1974), Johnson & Allred (1972), Williams & Berke (1986), Berke (1987, in part) and Sissom & Stockwell (1991).

Figure 47: Map showing distribution of genus Stahnkeus. Individual localities based on specimens examined, Williams (1970a, 1980: fig. 98, in part), Berke (1987, in part) and Sissom & Stockwell (1991).

Figure 48: Stahnkeus subtilimanus, male, dorsal view, Split Mountain, ABDSP, California, USA.

Figures 17–32: Examples of the female pecten of genera Serradigitus and Stahnkeus showing the varied configurations of the basal teeth. 17. Serradigitus wupatkiensis. 18. S. adcocki. 19. S. torridus. 20. S. calidus. 21. S. bechteli. 22. S. g. gertschi. 23. S. minutis. 24. S. littoralis. 25. S. hearnei. 26. S. joshuaensis. 27. S. haradoni. 28. S. gramenestris. 29. S. pacificus. 30. Stahnkeus harbisoni. 31. S. subtilimanus. 32. S. deserticola. Figs. 20, 22, 26, 30–32 after Soleglad (1974, in part).