Limbodessus morgani
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 morgani

description: <i>Limbodessus morgani</i> (Watts &amp; Humphreys, 2000) (Figs 148–161) <b>Source of material.</b> One specimen of instar I and one of instar II were used for the description (Table 1). Larvae were collected in association with adults at the following locality: <b>Australia, Carey palaeovalley</b>, Uramurdah Lake calcrete, NE Lake Way, No 7, site 285, BES 6450, 26.85444S, 120.33833E, 9-V-2001, coll. W. F. Humphreys, C. H. S. Watts and S. J. B. Cooper. <b>Diagnosis (instar II).</b> Smaller species (HL less than 0.40 mm); head subpentagonal; nasale subtriangular; halfcircle 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 1.75); 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. <b>Instar I</b> (Figs 148–161). Head (Figs 148–156). 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 less than 2.05 times longer than A2; MP2 more than 2.10 times longer than MP1; MP2 1.95–2.65 times longer than MP3; LP2 more than 2.40 times longer than LP1. Legs (Figs 157–158). L3 less than 2.85 times longer than HW. Abdomen (Figs 159–161). U more than 3.75 times longer than LAS; U less than 2.35 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 <b>Instar II.</b> Head. A3 less than 2.50 times longer than A1; A4 more than 0.75 times as long as A3; MN less than 4.70 times longer than broad; MP2 1.05–1.45 times longer than MP1; MP2 less than 2.05 times longer than MP3; LP2 more than 1.75 times longer than LP1. Legs. L3 less than 2.20 times longer than HW; CL(L3) more than 0.40 times as long as TA. Abdomen. U 3.00–4.00 times longer than LAS; U less than 2.15 times longer than HW; U1 less than 1.45 times longer than U2. Chaetotaxy. Anteroventral margin of nasale with 22 lamellae clypeales distributed in a single row; anterior secondary setae on proCO absent; meso- and metaCO with less than 5 posterodorsal secondary setae; ventral secondary setae on proCO absent; ventral secondary setae on mesoCO present; proFE with less than 3 posteroventral secondary setae; metaFE with less than 11 secondary setae; secondary setae on proTI absent; anterodorsal secondary setae on meso- and metaTI present; meso- and metaTI with less than 2 posterodorsal secondary setae; posteroventral secondary setae on meso- and metaTI absent; metaTI with less than 5 secondary setae; secondary setae on proTA absent; posterodorsal secondary setae on meso- and metaTA present; posteroventral secondary setae on meso- and metaTA absent; metaTA with less than 4 secondary setae; secondary setae on U absent. Measurements and ratios that characterize the body shape are shown in Table 6. Secondary leg setation detailed in Table 14. <b>Instar III.</b> Not available. <b>Remarks.</b> The absence of instar III specimens of <i>L. morgani</i> hampers the comparison with the other species described here, particularly regarding the chaetotaxic characters. <i>Limbodessus morgani</i> has a small size and belongs to the group of stygobitic species that lack secondary setae on the urogomphus (<i>L. challaensis</i>, <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. ordinarius</i>, <i>L. pulpa</i>, <i>L. raeae</i>, <i>L. windarraensis</i>, <i>L. yuinmeryensis</i>). Within this group, it can be separated by the following combination of characters: lateral margins of the nasale not inflated in dorsal view, and claws relatively longer as compared to tarsus (ratio CL/TA&gt; 0.40). This last feature separates <i>L. morgani</i> from all other stygobitic species studied except <i>L. fridaywellensis</i>.
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 66-69, DOI: 10.11646/zootaxa.3584.1.1