Unixenus karajinensis, Short, Megan & Huynh, Cuong, 2011

Short, Megan & Huynh, Cuong, 2011, The genus Unixenus Jones, 1944 (Diplopoda, Penicillata, Polyxenida) in Australia, ZooKeys 156, pp. 105-122 : 113-117

Unixenus karajinensis sp. n. Figs 1C45

Holotype.

Male, Wittenoom Gorge, asbestos mine, WA, 22°19'S, 118°19'E, 20 May 1977, WD Temperton, WAM T71106, mounted on slide.

Paratypes.

Six females same data as holotype, on six slides, WAM T116452-7; four females and three males from Tom Price, WA, 22°41'S, 117°47'E, 727 m, 6 February 1978, CE Chobanoff, females: WAM T116458-61, males: WAM T116462-64, mounted on slides.

Other material.

Additional specimens, same data as holotype, WAM T116451; additional specimens, same data as paratypes from Tom Price, WAM T116465; AM collection from Hamersley Ranges, WA, 10 km north from Tom Price turnoff along Nanutarra - Wittenoom Rd, on left side, 22°32'21"S, 117°38'01"E, 25 May– 4 June 2004, M. Bulbert et al., pitfall traps, AM KS111219.

Diagnosis.

Differs from Unixenus mjoebergi in longer and thinner tergal trichomes, 6 pairs of coxal glands in males on leg pairs 6-11, telotarsus with anterior spinous projection shorter than claw, 8 ornamental trichomes c each side. Antennal articles VI and VII with distinctive notched appearance at distal edge, arrangement of sensilla in article VI with setiform sensillum anterior to 3 basiconic sensilla. Number of setae on coxae 3-13 varies more widely from 1-6 in contrast to 2-3 in Unixenus mjoebergi . The hooked caudal trichomes have double barbs proximal to the hooks, last sternal plate with 2 setae.

Etymology.

The Australian aboriginal Banyjima people’s name for the Hamersley Ranges is Karajini.

Description.

Length of both sexes 2.8-3.3 mm, caudal bundle 0.3 mm.

Colouration in alcohol both sexes yellow brown with trichomes including caudal bundle medium to dark brown, long ornamental trichomes darker.

Head with 8 ocelli each side: 4 dorsal, 4 lateral (1 anterior, 2 medial and 1 posterior). Vertex with 2 posterior groups of trichomes arranged in 3 oblique rows (Fig. 4A). Number of trichomes varies, holotype with 40+38 trichomes, comprising: 8+8 (anterior rows), 21+20 (middle rows) and 11+10 (posterior rows). Total numbers each side varied: Tom Price paratypes 27-45 (n = 7); Wittenoom paratypes 25-35 (n = 6). Overall, both sexes showed highly variable number vertex trichomes (51-85), with asymmetrical pattern of 1-2 trichomes difference (occasionally up to 5). Trichobothria equal in size, arranged in shape of isosceles triangle with greater width a–c.

Antennae with proportions of 8 articles and 4 sensory cones typical of other species in genus (Figs 4B and 5B). Antennal articles VI and VII with distinctive notched appearance at distal edge (Fig. 5A), article VI with 3 thick basiconic sensilla of equal length, coeloconic sensillum posterior to basiconic sensilla, setiform sensillum anterior to basiconic sensilla. Antennal segment VII typical of genus with 1 coeloconic sensillum to the posterior followed anteriorly by 2 thick basiconic sensilla of similar height; 1 setiform sensillum between the basiconic sensilla (Fig. 4C). Clypeo-labrum with 12 setae along posterior margin, anterior margin with no dentition lateral to median cleft, two thirds surface covered with spherical papillae, papillae reducing in size to the posterior margin and lacking hairs (Fig 4D). Gnathochilarium with length lateral palp at least 2 X diameter medial palp; lateral palp with 13 cylindrical sensilla, medial palp 21 sensilla (Figs 4E and 5E).

Collum with almost symmetrical arrangement of trichomes, posterior row of trichomes with broad medial gap, extending to lateral clusters of trichomes, anteriorly a narrowing band of trichomes extending from each lateral cluster towards midline, scattered trichomes between posterior row and anterior bands (Fig. 4F). Number of trichomes 56L + 59R in holotype male; variation common with range per side: Wittenoom female paratypes 31-46 (n = 6); Tom Price paratype females 33-47 (n = 4), paratype males 37-43 (n = 3). Small lateral protuberances each with row of 6 forward-facing trichomes in holotype, varying between 4-6 in Tom Price and Wittenoom paratypes.

Trichomes of tergites 2-9 arranged on posterior half of tergite, 1 distinct posterior row with medial gap, merging with clusters laterally. Further trichomes anteriorly, loosely arranged in 2 to 3 rows. Anterior trichomes directed towards head while remaining trichomes directed posteriorly. Number of trichomes on tergite 2 in holotype male 61L+54R, variation common with range per side: Wittenoom paratype females 36-49 (n = 4); Tom Price paratype females 38-64 (n = 3), paratype males 49-52 (n = 2). Tergite 10 with wide medial gap, large clusters of trichomes either side, posterior rows forming part of each cluster (Fig 4F). Conical pleural projections along each side associated with tergites 2-10, each with dense cluster of trichomes. Tergal and pleural trichomes, long and thin with 2 internal rows projections (Figs 4L and 5F), tergal trichomes increasing in length posteriorly.

Legs 1 and 2 without trochanter, leg 1 also lacks tarsus 1. Trochanter and postfemur and tarsus 1 lack setae. Chaetotaxy as follows: coxa 1, 1 seta, coxa 2, 2 setae, coxae 3-13, 1-6 setae; prefemur, tibia and tarsus 2 with 1 seta, femur with 2 setae (Fig. 4G). Last sternal plate with 2 setae. Coxa, prefemur and femur with bi-articulate setae similar to those for Unixenus mjoebergi with longitudinal ridges on basal funicle, each ridge extending distally in a long, thin projections which surround the base of the flagellum (Figs 4H and 5C), setae of tibia and tarsus 2 setiform. Telotarsus bearing anterior spinous projection shorter than claw which bears posterior and anterior processes, large lamella process present (Fig. 4I). Males with 6 pairs coxal glands, leg pairs 6-11.

Telson with ornamental trichomes arranged almost symmetrically with 5 trichomes (some variants with 4-8) a, 1b, and 8c each side of midline (Fig. 4J). Insertion points vary in size with a and c bigger than b. Single caudal bundle of hooked trichomes with 2-4 hooks and barbed stems. Double barbs of stem showing both distal- and proximal-facing barbs (Fig. 4K). Double barbs start immediately below hooks on 4 hook trichomes, with simple distal-facing barbs before first double barb on 2-3 hook trichomes. In immature stadia, two clusters of short barbate trichomes with same structure as ornamental trichomes a found ventral to caudal bundle (Fig. 5D). These clusters also observed in other species in the family Polyxenidae . They displace laterally after moulting to become pleural projections.

Distribution.

This species is only known from three sites in the Hamersley Ranges, WA (Fig. 8). Both males and females were collected at each location. Since collection, the asbestos mine at Wittenoom has been closed and access restricted to the area that includes the type locality.

Remarks.

The widespread distributions of Unixenus attemsi , Unixenus mjoebergi and Unixenus corticolus sp. n. are not unexpected as their small size, bristles and very light weight make it probable that they are blown by the wind or become attached to bird feathers. Unexpectedly Unixenus karajinensis sp. n. appears to be limited to a single mountain range, although further sampling may extend the distribution.