Barretthydrus tibialis Lea, 1927

(Figs. 1–14, 16–19)

Source of Material. Larvae were collected in association with adults at the following localities: Australia, New South Wales, 20 km North of Nelligan, 15-VIII.1997, coll. C. H. S. Watts; Sardine Creek, 30 km North of Orbost V, 30-XI-1998, C. H. S. Watts leg.

Diagnostic Combination (Instar III). The third instar of B. tibialis can easily be distinguished from that of the closely similar B. geminatus by the presence of a broad, blackish macula on the anterior portion of the frontoclypeus (Fig. 16) in addition to a relatively shorter head capsule compared to the length of abdominal segment VIII (HL/LAS <4.50 compared to>4.60) and a larger total number of secondary setae on selected leg articles (Table 3).

Instar I

(Figs. 1–12)

Description. Color: [Not available owing to the bad state of preservation of the only specimen available.] Body: Measurements and ratios that characterize the body shape in Table 1. Head: Head capsule as in Figs. 1–2, HL = 0.60 mm, HL/LAS = 4.61. Abdomen: As in Figs. 10–11, U 1 = 0.75 mm; U1/HW = 1.55.

Instar II

No specimen available for study.

Instar III

(Figs. 13–14, 16–19)

Description. Color: Head capsule predominantly yellow; frontoclypeus with a broad, black, subapical macula (Fig. 16); head appendages dark yellow; thoracic tergites dark brown; abdominal tergites I, IV – VII dark brown, II and III dark yellow to pale brown and VIII pale yellow; urogomphi dark yellow to pale brown; legs dark brown proximally, pale yellow distally. Body: Measurements and ratios that characterize the body shape in Table 1. Head: Head capsule as in Fig. 16, HL = 1.24–1.30, HL/LAS <4.50. Abdomen: U1 = 1.51–1.69 mm, U1/HW = 1.56–1.67 (Fig. 19). Chaetotaxy: ProFE with more than 52 secondary setae; mesoFE with more than 56 secondary setae; mesoTI with more than 47 secondary setae; mesoTA with more than 34 secondary setae; metaCO with more than 26 secondary setae; metaFE with more than 66 secondary setae; metaTI with more than 50 secondary setae; metaTA with more than 43 secondary setae.