Limbodessus bigbellensis
Creators: name: Michat, Mariano C.
name: Alarie, Yves
name: Watts, Chris H. S.
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Dytiscidae
Limbodessus
Limbodessus bigbellensis

description: <i>Limbodessus bigbellensis</i> (Watts &amp; Humphreys, 2000) (Figs 31 –48) <b>Source of material.</b> Two specimens of instar I and two of instar III were used for the description (Table 1). Larvae were collected in association with adults at the following localities: <b>Australia, Murchison palaeovalley</b>, Austin Downs calcrete, PAT 7, BES 5559, 27.41333S, 117.04444E, 4–V–2001, coll. W. F. Humphreys, C. H. S. Watts and S. J. B. Cooper; Austin Downs calcrete, bore PAT 7, BES 9407, 27.41337S, 117.71122E, 14–VI–2002, coll. W. F. Humphreys and R. Leys. <b>Diagnosis (instar III).</b> Larger species (HL more than 1.25 mm); head (Fig. 45) 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 scarce (20 or less); occipital foramen strongly reduced (HW/OCW more than 2.85); occipital suture present; lateral margins of parietal straight; secondary spiniform setae on lateral margins of parietal scarce; seta AN2 present; distal half of MN broad; setae LA3, LA4, LA5 and LA8 robust; secondary setae on U present (Fig. 48). <b>Instar I</b> (Figs 31 –44). Head (Figs 31–39). Cephalic capsule not strongly elongate (HL/HW less than 1.55); seta PA3 inserted far from setae PA1 and PA2; A3 2.20–2.75 times longer than A1; A3 more than 2.25 times longer than A2; MP2 less than 1.45 times longer than MP1; MP2 1.95–2.65 times longer than MP3; LP2 1.40–2.00 times longer than LP1. Legs (Figs 40–41). L3 more than 2.95 times longer than HW. Abdomen (Figs 42–44). U more than 3.75 times longer than LAS; U less than 2.35 times longer than HW; U1 more than 1.45 times longer than U2. Chaetotaxy. Frontoclypeus with 14 lamellae clypeales; additional setae on U absent. Measurements and ratios that aspect; 37, right mandible, dorsal aspect; 38, labium, dorsal aspect; 39, labium, ventral aspect. EB, egg burster; Sp, spinula; TP, tentorial pit. Scale bars = 0.08 mm. <b>Instar III</b> (Figs 45–48). Head (Fig. 45). 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 more than 1.75 times longer than labial palpus; MP2 3.20–4.00 times longer than MP3; LP2 less than 0.60 times as long as LP1. Legs (Figs 46–47). L3 more than 2.85 times longer than HW. Abdomen (Fig. 48). U more than 3.10 times longer than LAS; U 1.55–2.25 times longer than HW; U1 more than 3.35 times longer than U2. Chaetotaxy. Anteroventral margin of nasale with 61 lamellae clypeales distributed in 2 rows; pro- and mesoCO without anterior secondary setae; pro-, meso- and metaCO without posterior secondary setae; proCO with less than 11 secondary setae; metaCO with less than 20 secondary setae; anterodorsal secondary setae on pro- and metaFE present; metaFE with less than 12 anteroventral secondary setae; posterodorsal secondary setae on meso- and metaFE absent; metaFE with 9–27 secondary setae; anterodorsal, anteroventral and posterodorsal secondary setae on proTI present; mesoTI with less than 4 anteroventral secondary setae; metaTI with less than 9 anteroventral secondary setae; metaTI with less than 16 secondary setae; anterodorsal secondary setae on proTA present; anterodorsal secondary setae on meso- and metaTA absent; anteroventral and posterodorsal secondary setae on proTA absent; anteroventral secondary setae on meso- and metaTA present; posterodorsal secondary setae on meso- and metaTA present; posteroventral secondary setae on pro- and mesoTA present; metaTA with 1–5 posteroventral secondary setae; proTA with 1–7 secondary setae; mesoTA with more than 7 secondary setae; metaTA with less than 16 secondary setae; secondary setae on U present. Measurements and ratios that characterize the body shape are shown in Table 8. Secondary leg setation detailed in Table 16. <b>Remarks.</b> <i>Limbodessus bigbellensis</i> belongs to the group of stygobitic species characterized by the presence of secondary setae on the urogomphus (<i>L. barwidgeeensis</i>, <i>L. cooperi</i>, <i>L. eberhardi</i>, <i>L. macrohinkleri</i>, <i>L. nambiensis</i>, <i>L. raesideensis</i>, <i>L. yandalensis</i>) (Fig. 48). Within this group, it can be distinguished by the following combination of characters: head pyriform (Fig. 45), occipital suture present (Fig. 45), occipital foramen strongly reduced (Fig. 45), absence of anterior secondary setae on the procoxa (Fig. 46), absence of posterodorsal secondary setae on the meso- and metafemur, and presence of anterodorsal secondary setae on the protarsus (Fig. 46).
description: Published as part of <i>Michat, Mariano C., Alarie, Yves &amp; Watts, Chris H. S., 2012, 3584, pp. 1-110 in Zootaxa 3584 (1)</i> on pages 27-31, DOI: 10.11646/zootaxa.3584.1.1