Limbodessus yandalensis Watts & Humphreys, 2006

Michat, Mariano C., Alarie, Yves & Watts, Chris H. S., 2012, 3584, Zootaxa 3584 (1), pp. 1-110 : 89

Limbodessus yandalensis Watts & Humphreys, 2006

(Figs 234–237)

Source of material. One specimen of instar III was used for the description ( Table 1). The larva was collected in association with adults at the following locality: Australia, Carey palaeovalley, Yandal calcrete, MEB site 128, BES 10345, 27.76413S, 121.02592E, 23–III–2004, coll. W. F. Humphreys and S. J. B. Cooper.

Diagnosis (instar III). Larger species (HL more than 1.25 mm); head (Fig. 234) pyriform; nasale digitiform; half-circle of dense spinulae on lateroventral margins of nasale absent; hole-like structure on ventrodistal surface of nasale absent; lateral margins of nasale not inflated in dorsal view; lateral branches of nasale well developed; slender spinulae anterior to seta FR13 numerous (25 or more); occipital foramen strongly reduced (HW/OCW more than 2.85); occipital suture absent; lateral margins of parietal curved; secondary spiniform setae on lateral margins of parietal numerous; seta AN2 present; distal half of MN broad; setae LA3, LA4, LA5 and LA8 hair-like; secondary setae on U present (Fig. 237).

Instar I. Not available.

Instar II. Not available.

Instar III (Figs 234–237). Head (Fig. 234). A3 less than 2.25 times longer than A1; A3 less than 1.45 times longer than A2; MN less than 4.85 times longer than broad; MP less than 1.75 times longer than labial palpus; MP2 more than 4.30 times longer than MP3; LP2 more than 0.65 times as long as LP1. Legs (Figs 235–236). L3 2.25– 2.85 times longer than HW. Chaetotaxy (Fig. 237). Anteroventral margin of nasale with 206 lamellae clypeales distributed in 3 rows; proCO with 1–4 anterior secondary setae; mesoCO without anterior secondary setae; pro-, meso- and metaCO without posterior secondary setae; proCO with 12–15 secondary setae; metaCO with less than 20 secondary setae; anterodorsal secondary setae on pro- and metaFE present; metaFE with more than 12 anteroventral secondary setae; posterodorsal secondary setae on meso- and metaFE absent; metaFE with more than 30 secondary setae; anterodorsal, anteroventral and posterodorsal secondary setae on proTI present; mesoTI with more than 4 anteroventral secondary setae; metaTI with more than 9 anteroventral secondary setae; metaTI with more than 18 secondary setae; anterodorsal secondary setae on pro-, meso- and metaTA absent; anteroventral and posterodorsal secondary setae on pro-, meso- and metaTA present; posteroventral secondary setae on pro- and mesoTA present; metaTA with more than 8 posteroventral secondary setae; proTA with more than 9 secondary setae; mesoTA with more than 7 secondary setae; metaTA with more than 18 secondary setae; secondary setae on U present. Measurements and ratios that characterize the body shape are shown in Table 12. Secondary leg setation detailed in Table 20.

Remarks. The only specimen of L. yandalensis examined had the second urogomphomere broken, which prevented the evaluation of urogomphal morphometry. Limbodessus yandalensis is a very characteristic stygobitic species that belongs to the group of species characterized by the presence of secondary setae on the urogomphus ( L. barwidgeeensis , L. bigbellensis , L. cooperi , L. eberhardi , L. macrohinkleri , L. nambiensis , L. raesideensis ) (Fig. 237). Within this group, L. yandalensis can be distinguished by the following combination of characters: head pyriform (Fig. 234), occipital suture abesent (Fig. 234), occipital foramen strongly reduced (Fig. 234), presence of anterior secondary setae on the procoxa (Fig. 235), absence of posterodorsal secondary setae on the meso- and metafemur, presence of anterodorsal secondary setae on the protibia (Fig. 235), and absence of anterodorsal