Hydroglyphus balkei Hendrich
Creators: name: Michat, Mariano C.
name: Alarie, Yves
name: Watts, Chris H. S.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Dytiscidae
Hydroglyphus
Hydroglyphus balkei

description: Hydroglyphus balkei Hendrich, third-instar larva
Source of material. Australia; Watson, 14 km W Herberton Qld., 31/iii/1996; C. H. S. Watts.
Diagnosis. Antennomere 3 with a ventroapical spinula (Fig. 17); pore PAj absent; U without secondary setae (Fig. 25); absence of anterior secondary setae on CO and presence of 8–9 secondary setae on mesoFE (Table 2); ratios A4/A3, LP2/LP1, L3/L1, L3/HW and LAS/HW (Table 1).
Description. Color. Head capsule pale yellow, area posterior to occipital suture light brown, V-shaped band contiguous to ecdysial line light brown; head appendages pale yellow, mandible light brown; thoracic tergites pale yellow with light brown laterals, meso- and metatergite with a light brown anterior macula at each side of mid line; abdominal tergites I–VI predominantly pale yellow, with light brown laterals, sclerites VII–VIII predominantly light brown; membranous parts pale; legs pale yellow; urogomphus light brown.
Body. Subcylindrical, narrowing towards abdominal apex. Measurements and ratios that characterize the body shape are shown in Table 1.
Head. Head capsule (Fig. 15). Longer than broad; posterolateral surface covered with minute spinulae; maximum width posterior to stemmata, without neck constriction; occipital suture present; ecdysial line well marked, coronal line short; occipital foramen broadly emarginate ventrally; posterior tentorial pits visible ventrally; FR elongate, lateral margins sinuate; nasale moderately elongate, subtriangular, rounded apically, slightly sinuate laterally, with one small branch at each side; ventrodistal surface with spinulae of different shapes, ventrolateral margin with several robust spinulae; anteroventral margin of nasale with a half circle of 33–35 spatulate setae of different lengths, directed downward; six dorsolateral stemmata at each side forming a circle. Antenna (Figs 16–17). Elongate, composed of four antennomeres, shorter than HW; A4 the shortest, A2 and A3 the longest, subequal; A3 with a ventroapical spinula; A3’ relatively elongate. Mandible (Fig. 18). Prominent, broad basally, distal half projected inwards and upwards, apex sharp; mandibular channel present. Maxilla (Figs 19–20). Cardo fused to stipes; stipes short, broad; galea and lacinia absent; MP elongate, shorter than antenna, composed of three palpomeres, MP3 the shortest, MP1 and MP2 the longest, subequal. Labium (Figs 21–22). Prementum small, subtrapezoidal, somewhat broader than long, without lateral spinulae, anterior margin slightly indented medially; LP elongate, composed of two palpomeres; LP2 slightly longer than LP1.
Thorax. Terga convex, pronotum slightly shorter than meso- and metanotum combined, meso- and metanotum subequal; protergite subrectangular, more developed than meso- and metatergite; meso- and metatergite transverse, with anterotransverse carina; sagittal line well visible; sterna membranous; spiracles present on mesothorax. Legs (Figs 23–24). Long, composed of six articles sensu Lawrence 1991), L1 the shortest, L3 the longest; CO robust, elongate, TR divided into two parts, FE, TI and TA slender, subcylindrical, PT with two long, slender, slightly curved claws; posterior claw shorter than anterior claw on L1 and L2, posterior claw longer than anterior claw on L3; most surface of legs covered with minute slender spinulae in transverse rows; ventral surface of pro- and mesoTA and to a lesser extent pro- and mesoTI with elongate spinulae.
Abdomen. Eight-segmented; segments I–VI sclerotized dorsally, membranous ventrally; tergites I–VI narrow, transverse; segments VII–VIII completely sclerotized, ring-like; all sclerites without sagittal line, with anterotransverse carina, covered with minute spinulae in transverse rows; spiracles present on laterals of segments I–VII; LAS (Fig. 25) the longest, siphon short, subconical. Urogomphus (Fig. 25). Very long, composed of two urogomphomeres; U1 long, much longer than LAS, basal portion covered with minute spinulae; U2 narrow, setiform, shorter than U1.
Chaetotaxy. Head capsule with numerous secondary setae; parietal with 4–5 short, spine-like, secondary setae on each lateroventral margin; MN with one hair-like, secondary seta on basoexternal margin; thoracic and abdominal sclerites I–VII with several secondary setae, mainly on posterior half; secondary leg setation detailed in Table 2 and Figs 23–24; LAS with numerous spine-like secondary setae (Fig. 25). Primary chaetotaxy similar to that of generalized Hydroporinae larva (Alarie & Harper 1990; Alarie et al. 1990; Alarie 1991; Alarie & Michat 2007) except for the following features: pore FRc submarginal, contiguous to seta FR7; pores PAd, PAe and PAj absent; pore PAg present; pore ANf absent; setae MX 4, MX 8, MX 9 and MX 10 absent; seta MX 1 inserted distally on the stipes; seta LA7 absent; seta TR 2 absent; pore FEa absent; seta TI7 short, spine-like; pores ABa and ABc absent; seta AB10 spine-like; we were unable to find pore ABd and setae AB7 and AB8; however, we could not establish if they are really absent due to the presence of spinulae on the siphon; setae UR2, UR3 and UR4 inserted far from each other; setae UR5, UR6 and UR7 elongate; seta UR8 inserted distally.
description: Published as part of Michat, Mariano C., Alarie, Yves & Watts, Chris H. S., 2010, Descriptions of the first-instar larva of the hypogaeic species Neobidessodes limestoneensis (Watts & Humphreys) and of the third-instar larva of Hydroglyphus balkei Hendrich (Coleoptera: Dytiscidae: Bidessini) with phylogenetic considerations, pp. 38-50 in Zootaxa 2658 on pages 42-43, DOI: 10.5281/zenodo.198996