Atrophotergum sodalis Mesibov, 2004, n. sp.

Atrophotergum sodalis n. sp.

Figs. 3, 4, 10; map Fig. 12

Holotype: Male, Old Chum Dam, Tasmania, EQ880541 (41°03’33”S, 148°02’50”E), 100m, 18.vii.1989, P. Cale, QVM 23:25387, pitfall 14.3.

Paratypes: 2 males, Old Chum Dam, EQ878553 (41°02’55”S, 148°02’41”E), 180m, vi.2000, R. Bashford, AM KS87138, pitfall 12/2; 3 males, same details, QVM 23:25423, 1 dissected; 2 males, Retreat, EQ127474 (41°07’28”S, 147°09’04”E), 180m, 6.vii.1991, R. Mesibov, QVM 23:25400.

Other material examined: 67 males. See Appendix for details.

Diagnosis: Distinguished from other Atrophotergum spp. by the unique form of the gonopod, by the less well­defined somite 2 pit and by the absence of a ventrolateral swelling on antennomere 7 (see Remarks).

Description: As for genus, but the somite 2 pit, rather than being a relatively deep hollow with a well­defined, rounded rim, is a shallow excavation almost touching the paranotal margin (Fig. 3 B). Males 7–8 mm long, 0.6–0.7 mm in maximum vertical diameter. In alcohol, most specimens are pale with reddish head and antennae, collum margins and posterior margins of metatergites.

Gonopod telopodite (Fig. 10) gently curved posteriorly. Solenomerite a strap­like process curving laterally and posteriorly, divided at about half its length into an anterior branch containing the terminus of the prostatic groove and a shorter posterior branch; both branches have roughened surfaces. SF not extending posteriorly as far as in other Atrophotergum spp., its distal portion mesolaterally flattened and its basal portion dorsoventrally flattened. PDC projecting posteriorly and slightly laterally as a rod­like process with a short distal branch arising at a right angle at about one­third the length of the process; PBC curving distally. TT bent posteriorly and laterally, its tip reaching as far distally as the right­angled branch of the PDC process. MES more or less parallel to the long axis of the telopodite, mesolaterally flattened with a broad, smoothly notched tip. LES twisted so that its posterior corner is more mesal and basal than its anterior corner.

Anterior sternal process on somite 17 (Fig. 4 E) a very low eminence, undetectable at low magnification; posterior process a low eminence anteriorly, posteriorly a very short, finger­like structure directed ventrally and slightly posteriorly.

Distribution and habitat: Locally abundant in leaf and woody litter in dry and wet eucalypt forest over at least 5 0 0 0 km 2 in northeast Tasmania, including Flinders Island in Bass Strait, from near sea level to ca. 800 m (Fig. 12). There is also one record of this species from Pinus radiata litter in a 35 year­old forest plantation near Warrentina.

Etymology: Latin sodalis, comrade, noun in apposition; for the ‘Old Chum’ of the type locality.

Remarks: In the other five known Atrophotergum spp., there is a ventrolateral swelling on antennomere 7 (Fig. 1 B) which carries a number of short, stout sensilla. The sensilla are present in A. sodalis but not the swelling.