Tropisternus collaris (Fabricius)

Torres, Patricia L. M., Michat, Mariano C. & Archangelsky, Miguel, 2008, Description of the preimaginal stages of three species of the genus Tropisternus Solier, subgenus Strepitornus Hansen (Coleoptera: Hydrophilidae), with emphasis on morphometry and chaetotaxy, Zootaxa 1702, pp. 1-25 : 14-15

Tropisternus collaris (Fabricius)

( Figs. 2 , 20 )

Material examined. ARGENTINA: Entre Ríos Province: “El Palmar” National Park, breeding adults collected on 27.II.2002 by P. L. M. Torres (2 egg cases, 7 instar I, 3 instar II and 5 instar III larvae, 8 pupae, 5 emerged adults).

Egg case. Length = 4.00– 4.50 mm, width = 3.00–4.00 mm, height = 5.00– 5.50 mm ( Fig. 2 ); cap length = 3.50 mm; mast length = 9.50 mm. MastL/capL = 2.71.

First-instar larva. Morphometric measures detailed in Table 1; chaetotaxy of legs summarized in Table 2.

Second-instar larva. Morphometric measures detailed in Table 1.

Antenna. A1 with 16–17 short secondary setae on ventral surface, 16–17 stout secondary setae on inner margin, 6–7 short thin secondary setae on outer margin and dorsal surface; apical upper ring with 4 secondary setae, lower one with 9–10 secondary setae.

Maxilla. Outer margin of stipes with 2–3 stout secondary setae basally and 5–7 thin secondary setae unevenly distributed.

Labium. Mt with 1 stout secondary seta on each anterolateral edge, 4–7 secondary setae on laterobasal edges, 15–18 stout secondary setae on dorsal surface, and 2–6 secondary setae on ventral surface.

Legs. Chaetotaxy summarized in Table 2.

Third-instar larva. Morphometric measures detailed in Table 1.

Antenna. A1 with 7–10 short secondary setae on ventral surface, 16–17 stout secondary setae on inner margin; apical upper ring with 3–5 secondary setae, lower one with 9–11 secondary setae.

Maxilla. Outer margin of stipes with 1–3 stout secondary setae basally and 5–7 thin secondary setae unevenly distributed.

Labium. Mt with 1 stout secondary seta on each anterolateral edge, 6–8 secondary setae on laterobasal edges, 15–18 stout secondary setae on dorsal surface, and 2–4 secondary setae on ventral surface.

Legs. Chaetotaxy summarized in Table 2.

Pupa. TL (excluding pronotal styli and cerci) = 9.00– 10.20 mm; MW = 4.50–5.00 mm. Pronotum with 20–22 styli distributed as follows: 2 on pronotal disc and 18–20 on margins (8–10 large styli on anterior margin, 2 on each posterolateral angle and 6 along posterior margin).

Figures

FIGURES 1 – 3. Egg cases of Tropisternus: 1, T. scutellaris; 2, T. collaris; 3, T. parananus. Scale bar = 2.0 mm.

FIGURES 19 – 21. Head capsule of third-instar larvae of Tropisternus, dorsal view: 19, T. scutellaris; 20, T. collaris; 21, T. parananus. Scale bar = 0.5 mm.