Limbodessus challaensis
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 challaensis

description: <i>Limbodessus challaensis</i> (Watts &amp; Humphreys, 2001) (Figs 49 –66) <b>Source of material.</b> One specimen of instar I and one 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>, Challa North calcrete, Nyung Well, BES 7251, 27.98833S, 118.5175E, 3–V–2001, coll. W. F. Humphreys, C. H. S. Watts and S. J. B. Cooper; Challa North calcrete, Nyung Well, BES 10386, 27.98842S, 118.51750E, 25–III–2004, coll. W. F. Humphreys and S. J. B. Cooper. <b>Diagnosis (instar III).</b> Medium-sized species (HL 0.55–1.15 mm); head (Fig. 63) subpentagonal; nasale subtriangular; 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 minute; slender spinulae anterior to seta FR13 scarce (20 or less); occipital foramen well developed (HW/OCW less than 1.90); 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 hair-like; secondary setae on U absent (Fig. 66). <b>Instar I</b> (Figs 49–62). Head (Figs 49–57). Cephalic capsule not strongly elongate (HL/HW less than 1.55); seta PA3 inserted contiguous to setae PA1 and PA2; A3 more than 2.80 times longer than A1; A3 more than 2.25 times longer than A2; MP2 less than 1.45 times longer than MP1; MP2 less than 1.85 times longer than MP3; LP2 1.40–2.00 times longer than LP1. Legs (Figs 58–59). L3 less than 2.85 times longer than HW. Abdomen (Figs 60– 62). U more than 3.75 times longer than LAS; U more than 2.45 times longer than HW; U1 less than 1.05 times longer than U2. Chaetotaxy. Frontoclypeus with 12 lamellae clypeales; additional setae on U absent. Measurements and ratios that characterize the body shape are shown in Table 2. <b>Instar II.</b> Not available. <b>Instar III</b> (Figs 63–66). Head (Fig. 63). A3 less than 2.25 times longer than A1; A3 less than 1.45 times longer than A2; MN more than 4.85 times longer than broad; MP less than 1.75 times longer than labial palpus; MP2 less than 2.00 times longer than MP3; LP2 more than 0.65 times as long as LP1. Legs (Figs 64–65). L3 2.25–2.85 times longer than HW. Abdomen (Fig. 66). U 2.40–3.10 times longer than LAS; U 1.55–2.25 times longer than HW; U1 0.70–1.40 times as long as U2. Chaetotaxy. Anteroventral margin of nasale with 51 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 secondary setae on proTI present; anteroventral and posterodorsal secondary setae on proTI absent; mesoTI with less than 4 anteroventral secondary setae; metaTI with less than 9 anteroventral secondary setae; metaTI with less than 16 secondary setae; secondary setae on proTA absent; anterodorsal and posteroventral secondary setae on meso- and metaTA absent; anteroventral and posterodorsal secondary setae on meso- and metaTA present; mesoTA with less than 7 secondary setae; metaTA with less than 16 secondary setae; secondary setae on U absent. 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 challaensis</i> belongs to the group of stygobitic species characterized by the absence of secondary setae on the urogomphus (<i>L. exilis</i>, <i>L. fridaywellensis</i>, <i>L. hillviewensis</i>, <i>L. hinkleri</i>, <i>L. leysi</i>, <i>L. masonensis</i>, <i>L. millbilliensis</i>, <i>L. morgani</i>, <i>L. ordinarius</i>, <i>L. pulpa</i>, <i>L. raeae</i>, <i>L. windarraensis</i>, <i>L. yuinmeryensis</i>) (Fig. 66). Larvae of <i>L. challaensis</i> can be distinguished from any other species of that group by the following combination of characters: lateral margins of the nasale not inflated in dorsal view (Fig. 63), mandible more than five times longer than broad, metacoxa with 1 secondary seta, presence of anterodorsal secondary setae on the protibia (Fig. 64), absence of anteroventral secondary setae on the protibia (Fig. 64), absence of secondary setae on the protarsus (Figs 64–65), presence of anteroventral secondary setae on the mesotarsus, and absence of posteroventral secondary setae on the tarsus (Fig. 65).
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 31-35, DOI: 10.11646/zootaxa.3584.1.1