Unixenus attemsi Nguyen Duy-Jacquemin & Conde , 1967

Short, Megan & Huynh, Cuong, 2011, The genus Unixenus Jones, 1944 (Diplopoda, Penicillata, Polyxenida) in Australia, ZooKeys 156, pp. 105-122 : 107-110

Unixenus attemsi Nguyen Duy-Jacquemin & Conde, 1967 Figs 1A23C, 3D

Unixenus attemsi Nguyen Duy-Jacquemin and Condé, 1967: 68, figs 9, 10.

Material examined.

Slide preparations were made of adults from the following localities: Marangaroo Conservation Area in Perth, WA, 31°49'48"S, 115°50'12"E, 9 February 2006, M. Short and C. Huynh, in Eucalyptus bark; Scott Creek, SA, 35°04'37"S, 138°42'29"E, 15 February 2005, M. Short and C. Huynh, litter under Eucalyptus ; Robinvale, Vic, 34°35'S, 142°46'E, 28 October -3 November 1968, T. Weir, J. Lawrence and E. Hansen, litter under Eucalyptus camaldulensis , ANIC berlesate 1085. Collections made by the authors will be deposited in WAM and MV.

Diagnosis.

This species can be distinguished from other species in the genus by the presence of 2 transverse rows only of short barbate trichomes on collum and tergites, 3 basiconic sensilla on antennal article VI, long lateral palps on gnathochilarium (2.5 X diameter of medial palp), 1 seta on femur and no setae on tibia, funicle of leg setae with no projecting spines, telotarsus with 4-6 processes on claw, thin anterior spinous projection same length as claw, 3 ornamental trichomes c each side, caudal hooked trichomes with 3-11 hooks with double pointed barbs on stem of trichomes with 4 or more hooks.

Remarks.

The original description by Attems (1911) was very brief. A redescription of the species by Nguyen Duy-Jacquemin and Condé (1967) was based on examination of two female specimens from Torbay in southern Western Australia (the type locality) held in the Zoology Museum, Hamburg, Germany (coll. by Hamburg S.W. Australia Expedition 1905). This description is detailed and clearly illustrated, but in light of recent collection of the species from eastern Australia and examination of large numbers of the species from a range of locations in WA, the species description can now be expanded and variation in some characters recorded.

Additional description.

Body unpigmented with exception of darkly pigmented medial longitudinal band on dorsal surface and darkly pigmented lateral projections. Trichomes including caudal bundle colourless (Fig. 1A). Body length from Robinvale and Scott Creek specimens 1.2-1.7 mm (n = 6), Perth 1.4-1.8 mm (n = 5), Walpole-Nornalup National Park, WA, WAM T71144, 2.3 mm; caudal bundle 0.3-0.4 mm. Variation noted in number of trichomes in rows on posterior vertex of head, between specimens and between left and right (as determined by examination of trichome inse rtion points). Specimens examined varied with numbers each side: Perth 16-19 (n = 5), Scott Creek 12-13 (n = 4), Robinvale 9-14 (n = 7), no difference between males and females, individual maximum difference between left and right sides of vertex = 2. Clypeo-labrum as previously described, with 8 setae most commonly observed along posterior margin, in contrast to 9 described by Nguyen Duy-Jacquemin and Condé (1967).

Collum showsvariation in trichome number: Perth 19-25 each side (n = 4), Scott Creek 16-19 (n = 2), Robinvale 15-16 (n = 1). Maximum variation between right and left sides on a single individual = 2. On tergite 2, trichome numbers varied (each side of midline): Perth 23-32 (n = 4), Scott Creek 19-23 (n = 4), Robinvale 20 (n = 1). Males with 2 pairs of coxal glands, leg pairs 8 and 9. Variation observed in number of ornamental trichomes a: Perth 7-10a (each side) (n = 5), Scott Creek 6-7a (n = 5), Robinvale males 4-5a (n = 2), females 6-9a (n = 2). Adult females described by Nguyen Duy-Jacquemin and Condé (1967) had 10 and 12 trichomes a each side. Circular indentation (labelled d) observed adjacent and external to each cluster trichomes c (Fig. 3C). This structure, also illustrated in Figure 3G in Condé and Jacquemin (1962) labelled ‘x’, is present in all adult specimens of the genus examined but function unknown. Telotarsus with 4 processes on claw rather than 6 processes previously observed ( Nguyen Duy-Jacquemin and Condé 1967) (Fig. 2).

Single caudal bundle of hooked trichomes, 2-11 hooks with barbed stems, size of hook and nature of barbed stem dependent on number of hooks: trichomes with 2-4 hooks, hooks large, all barbs on stem distal-facing similar to those in Unixenus mjoebergi (Fig. 3E), trichomes with 4-11 hooks, hooks smaller and with double barbs along stem proximally, with both proximal- and distal-facing points (Fig. 3D). Specimens examined by Nguyen Duy-Jacquemin and Condé (1967) had 5-7 hooks, with no description given of barbs along stem.

Distribution.

This species is widespread in Australia (Fig. 8) but appears to be most common in a range of habitats in southern WA. The most northerly collection is Bush Bay, WA, 25°07'03"S, 113°48'22"E, where it was collected together with Unixenus mjoebergi (WAM T71125). In eastern Australia the species appears to be restricted to dry woodlands. It is found under bark of Eucalyptus in small aggregations, often with many exuviae, as well as in dry leaf litter and under stones in treed areas on well-drained sandy or sandy loam soil.

Remarks.

The two Torbay specimens described by Nguyen Duy-Jacquemin and Condé (1967) are longer than almost all measured in this study, at 2.25 and 2.65 mm. Torbay is on the south coast of WA (Fig. 8) and a single specimen in the WAM collection (T71144) from Walpole-Nornalup National Park on the south coast of WA is also large (2.3 mm). All adults from eastern Australia are smaller. Smaller adults have fewer trichomes on head and vertex.