Poltys columnaris, Thorell, 1890

Smith, H. M., 2006, A Revision of the Genus Poltys in Australasia (Araneae: Araneidae), Records of the Australian Museum 58, pp. 43-96 : 62

The Poltys columnaris species group

The Poltys columnaris -group appears to be rather complex. The genitalia of the two Australian species are similar, especially in females, but the huge eye tubercle of P. jujorum n.sp. is distinctive, being far longer than in P. milledgei . These two species are also well separated genetically, at least in COI sequences. At least six species from the P. columnaris -group have been described from SE Asia and the Asian mainland. Three of these species, P. columnaris Thorell , P. turriger Simon and P. squarrosus Thorell , are similar in characters and may prove to be conspecific but the variation in eye position in these individuals almost bridges the gap between the two Australian species.Although existing names should be used if possible, both Australian species have been described as new because neither perfectly matches any of these types and it may be many years before suitable material is available to resolve this problem. A single male from Borneo, which may belong to one of these Asian species, is discussed below; this is definitely distinct from the Australian species. Another closely related SE Asian type is P. pogonias Thorell from the Nicobar Islands. This subadult female is also close to P. milledgei , except that there is no sign of the sclerotized eyespot-like maculae, which are visible on the abdomen of every other specimen examined (see below), and the eye arrangement is outside the variation seen in other specimens. Given the isolation of the Nicobar Islands, and several other apparent cases of speciation seen in island Poltys specimens examined during the course of this study, there is a good chance that this is an endemic species.

All Poltys columnaris -group species females have an extremely short and broad epigyne and most have rows of shiny black maculae on the dorsal abdomen, just anterior to the spinnerets ( Figs 94, 124). These “eyespots” are smooth clear cuticular lenses that lie over black pigment spots. In living and well-preserved specimens, these can be extremely prominent and they may be used to deter predators as (at least from a human perspective down a microscope) they resemble rows of black, beady eyes. Some P. columnaris -group species also possess modified patellal spines, which as well as being flattened distally, are elongate and appear to have a weak fracture zone near the base of the shaft, at least in females ( Fig. 123, arrowed). Females of both Australian species have these spines, as well as most males of P. milledgei . Most of the older types are missing many spines and have not been assessed for this character. The two Australasian P. columnaris -group species, and four out of the other six described species, have a rather elongate eye tubercle with an anterior protuberance between the anterior eyes ( Figs 121, 223, 226, 229, 238). The remaining two species, P. turritus Thorell and P. raphanus Thorell (which will probably prove to be conspecific) have only a tiny bump between the PME ( Figs 232, 235). In the Australian species, at least, female abdominal shape is rather less variable than in the other species groups dealt with here.

Matched males are known only for the two Australasian species. The P. columnaris -group male mentioned above from Borneo ( RMNH ex coll. CLD) has eye tubercle proportions quite different to the Australian species. The palpal organs of this specimen show the same general features as seen in the two Australian species, with a proportionately long MA, a broad, dorsal TA, and a reduced, prolaterally displaced, conductor. The palpal characters are intermediate between the two Australian species, but somatic features are distinctive.