Unixenus myallensis Short & Huynh

Short, Megan & Huynh, Cuong, 2013, Four new species of Unixenus Jones, 1944 (Diplopoda, Penicillata, Polyxenida) from Australia, ZooKeys 278, pp. 75-90 : 83-86

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Unixenus myallensis Short & Huynh

sp. n.

Unixenus myallensis Short & Huynh   ZBK sp. n. Fig. 4 A–K


Female, Myall Lakes National Park, 3.8 km South of Mungo Brush campsite, NSW, 32°34'46"S, 152°17'27"E, ca 300-500 m, wet pitfall traps 14-24 May 1998, collected by L. Wilkie, AM KS.93670. Specimen mounted on slide, deposited in AM.


Male subadult stadium VII, same collection as holotype, AM KS.94096.

Female, same site as holotype, wet pitfall traps 26 November 1997, collected by L. Wilkie, AM KS.93660. Male adult, Male subadult stadium VII, Female subadult stadium VII, Wyrrabalong National Park, NSW, 33°16'47"S, 151°32'40"E, wet pitfall traps 27 November 1997, collected by L. Wilkie, AM KS.93662, KS.119556, AM KS.93663. All paratypes mounted on slides, deposited in AM.

Other material:

1 immature stadium IV (6 pairs legs), same site as holotype, wet pitfall traps 14 May 1998 collected by L. Wilkie, KS.93665. 1 stadium VI, 10 pl, sex unknown, Wyrrabalong National Park, NSW, 33°16'48"S, 151°32'45"E, wet pitfall traps 27 November 1997, collected by L. Wilkie, AM KS.93659. 1 stadium V, 8 pl, 1 stadium IV, 6 pl, Wyrrabalong National Park, NSW, 33°16'47"S, 151°32'40"E, wet pitfall traps 27 November 1997, collected by L. Wilkie, AM KS.93661, AM KS.93666. Preserved in ethanol in AM.


For Myall Lakes National Park, the type locality; adjective.


Similar chaetotaxy to Unixenus attemsi with 1 seta on femur and none on tibia, setae smooth biarticulate; differs from Unixenus attemsi in having a gap between anterior and posterior vertex groups of trichomes, 4 basiconic sensilla on antennal article VI, gnathochilarium with short lateral palps (1.5 × diameter of medial palp) bearing 12-13 short rounded sensilla, ornamental trichome insertions c in row.


As for Unixenus carnarvonensis , differing in the following details:

Measurements: Body length 2.2-2.4 mm (n=3) with no differences between sexes. Caudal bundle 0.5 mm.

Colouration: No freshly collected specimens available. Specimens had been preserved in 70% ethanol. Body yellow brown in colour with black trichomes including caudal bundle dark brown - black.

Two rows of trichomes either side of posterior vertex of head with number of trichomes in rows varying from 7-11 trichomes each side anteriorly, 4-6 each side in posterior rows. (Fig. 4A). Antennal article VI with 4 thick basiconic sensilla, coeloconic sensillum posterior to the basiconic sensilla, setiform sensillum between basiconic sensilla 1 and 2 (Fig. 4C). Clypeo-labrum with 6-9 setae along the posterior margin; anterior margin of labrum with 3-5 square shaped lamellar teeth each side of median cleft; tiny granular structures over labrum (Fig. 4E).

Gnathochilarium with lateral palp 1.5 times length of medial palp. Lateral palp with 12-13 sensilla, medial palp 22 sensilla (Fig. 4B), sensilla fat, cylindrical and short (2/3 length of Unixenus attemsi sensilla) (Fig. 4D).

Collum with two rows of trichomes sparsely arranged each side of a medial gap, rows merge laterally to form rosettes of trichomes, and with a small number (2 each side in holotype) of trichomes between the two rows. Lateral protuberances of collum with 3-4 trichomes each. Tergites 2-10 with trichomes arranged most commonly in 2 rows on posterior half of the tergite each side of a medial gap. Anterior row sinuous with small gap to lateral cluster. In posterior tergites the two rows are closer together and straighter (Fig. 4F). In some specimens tergites 2 and 3 have scattered trichomes between the anterior and posterior rows forming an intermediate 3rd row. Conical pleural projections along each side associated with tergites 2-10, each with dense cluster of short dark trichomes. Tergal trichomes of posterior tergites longer than those of anterior tergites.

Leg chaetotaxy as follows: coxa 1, one seta, coxa 2, 2 setae, coxae 3-13, 2-3 setae; prefemur, femur, 1 seta (Fig. 4G); setae biarticulate with glabrous funicle showing longitudinal ridging (Fig. 4I), tarsus 2 with small setiform seta (Fig. 4J), trochanter, postfemur, tibia and tarsus 1 lack setae, claw of telotarsus bearing posterior and anterior processes (Fig. 4H). Male with 2 pairs coxal glands on leg pairs 8 and 9.

Telson with ornamental trichome insertions numbering 5-6a, 1b and 3c each side of the midline, with c trichome insertions in straight line (Fig. 4K). Trichomes b and c black in colour. Hooked caudal trichomes with 1-6 hooks on barbed stems, majority with distal facing barbs only along stem proximal to hooks, with occasional double barbs with both distal and proximal facing projections (Fig. 4L).

Distribution. So far known only from two treed coastal sites in mid NSW, with a north-south range of ca 150 km (Fig. 5).