Limbodessus morgani (Watts & Humphreys, 2000)

Michat, Mariano C., Alarie, Yves & Watts, Chris H. S., 2012, 3584, Zootaxa 3584 (1), pp. 1-110 : 66-69

Limbodessus morgani (Watts & Humphreys, 2000)

( Figs 148–161 )

Source of material. 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: Australia, Carey palaeovalley, 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.

Diagnosis (instar II). 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.

Instar I ( 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

Instar II. 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.

Instar III. Not available.

Remarks. The absence of instar III specimens of L. morgani hampers the comparison with the other species described here, particularly regarding the chaetotaxic characters. Limbodessus morgani has a small size and belongs to the group of stygobitic species that lack secondary setae on the urogomphus ( L. challaensis , L. exilis , L. fridaywellensis , L. hillviewensis , L. hinkleri , L. leysi , L. masonensis , L. millbilliensis , L. ordinarius , L. pulpa , L. raeae , L. windarraensis , L. yuinmeryensis ). 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> 0.40). This last feature separates L. morgani from all other stygobitic species studied except L. fridaywellensis .

Figures

FIGURES 148–156. Limbodessus morgani, first-instar larva. 148, cephalic capsule, dorsal aspect; 149, cephalic capsule, ventral aspect; 150, right antenna, dorsal aspect; 151, left antenna, ventral aspect; 152, right maxilla, dorsal aspect; 153, left

FIGURES 157–161. Limbodessus morgani, first-instar larva. 157, left metathoracic leg, anterior aspect; 158, right