Ametor scabrosus, (HORN, 1873)

Archangelsky, Miguel, Martínez Román, Nicolás Rafael & Fikáček, Martin, 2021, Larval chaetotaxy and morphology are highly homoplastic yet phylogenetically informative in Hydrobiusini water scavenger beetles (Coleoptera: Hydrophilidae), Zoological Journal of the Linnean Society 192 (2), pp. 416-416 : 416-

AMETOR SCABROSUS (HORN, 1873)

( FIGS 35–43 )

Diagnosis

Larval morphology: Head capsule subquadrate with lateral margins slightly rounded; basal surface on dorsal and lateral sides bearing strong cuticular projections; frontal lines Y-shaped, coronal line short; nasale slightly asymmetrical, with four short teeth, median teeth smaller, left tooth slightly apart from remaining three, right tooth projecting farther than left one; lateral lobes of epistome symmetrical, bearing five stout setae and an inner area of strong and sharp cuticular projections; posterior tentorial grooves close to midline, anterior, close to submentum. Cervical sclerites present. Antenna short, basal antennomere the widest, as long as second antennomere; sensory appendage short, 0.2 × as long as third antennomere. Mandibles symmetrical, with three inner teeth at midlength, basal tooth the smallest. Maxilla with large stipes, slightly longer than palpus, inner margin with an area of short and sharp cuticular projections basally, distally bearing a strong and sharp spine; first palpomere incompletely sclerotized dorsally, bearing an inner appendage twice as long as second palpomere, third palpomere the longest; membrane between second and third palpomeres with several short and sharp cuticular projections. Labium with submentum fused to head capsule, dorsally with sharp cuticular projections on mentum, both palpomeres, and membranes between prementum and first palpomere and between first and second palpomeres, projections on membranes longer; mentum subtrapezoidal, wider basally; prementum subquadrate, slightly wider basally; ligula well developed, twice as long as first palpomere; second palpomere the longest, 3.0–3.5 × as long as first palpomere. Pronotal plate large, covering most of pronotum, subpentagonal, anterior margin straight, with sagittal line; those of meso- and metathorax smaller, irregularly shaped, both with sagittal line. Abdomen mostly membranous, segments one to seven with one anterior pair of small dorsal plates and a transverse row of small poorly sclerotized lobes some of them bearing a long distal seta, two additional pairs of projections on each lateral and lateroventral margin; dorsal plate of segment eight large, suboval; segment nine trilobed, sclerotized dorsally. Legs well developed, five-segmented. Morphometrics. See Table 3. Chaetotaxy. gFR2 with five stout setae projecting mediad; pores PA29 and PA30 on the same line; A2 with three setae near SE1; seta MN1 posterior to pore MN2; pore MN4 equidistant to seta MN1 and seta MN5; pore MN6 apparently present; setae MX 7– MX 11 distinguishable; pore LA11 basal.

Figures

Figures 35–43. Ametor scabrosus, first instar larva. 35–37, head capsule (35, dorsally; 36, ventrally; 37, labroclypeus). 38, antenna, dorsal view. 39, right mandible, dorsal view. 40–41, maxilla (40, dorsal view; 41, ventral view). 42–43, mentum and prementum (42, dorsal view; 43, ventral view). Scale bars: Figs 35–36: 0.1 mm, Figs 37–43: 0.05 mm.