Austrolimnius elatus

Román, Nicolás Martínez & Archangelsky, Miguel, 2017, Description of the mature larva of Austrolimnius nyctelioides (Germain, 1892) and A. elatus Hinton, 1941 (Coleoptera: Elmidae), Zootaxa 4216 (6), pp. 585-595 : 593

Austrolimnius elatus mature larva

Body ( Figs 3, 4 ) with sides subparallel, semicircular in cross-section. Color pale yellowish. Posterior margins of body segments with setiferous tubercles, dorsal ones 1.20–1.47 times as long as wide. Length: 3.5 mm; maximum width: 0.4–0.5 mm.

Head ( Figs 16–21 ): head capsule and head appendages similar to A. nyctelioides , except for: 1- mandibles ( Fig. 20 ), narrower at base, maximum length / maximum width ratio of 1.66; 2- cardo proportionally shorter ( Fig. 19 ), width / length ratio of 3.65; 3- stipes ( Fig. 19 ) 1.60-1,78 times as long as wide; 4- postmentum slightly shorter ( Fig. 19 ), 1.71–1.72 times as long as wide.

Thorax ( Figs 22 , 30 ): similar to A. nyctelioides , except for shorter and narrower prothorax, 1.64–1.86 times as wide as long.

Abdomen ( Figs 23–29 ) similar to A. nyctelioides , except for segment IX longer, 2.76–3.07 times as long as segment VIII.

Habitat. Esquel Viejo, Rodeo and La Cancha creeks are shallow streams, in northwestern Chubut province, Argentina and are located in the ecotone between the Subantarctic forest and the Patagonian steppe phytogeographical provinces. This area is characterized by a gramineous steppe (dominant species Festuca pallescens ) that gets into Nothofagus spp forest ( León et al., 1998).

Figures

FIGURE 30. Thorax of mature larva of Austrolimnius elatus, ventral view. Scale bar: 0.1 mm.

FIGURES 1 – 4. Habitus of mature Austrolimnius larvae. 1) dorsal view of A. nyctelioides; 2) ventral view of A. nyctelioides; 3) dorsal view of A. elatus; 4) ventral view of A. elatus. Scale bars, Figs 1 – 4: 1 mm.

FIGURES 16 – 21. Mature larvae of Austrolimnius elatus. 16) head capsule, dorsal view; 17) right mandible, ventral view; 18) antenna, dorsal view; 19) maxillo-labial complex, ventral view; 20) labrum, dorsal view; 21) labrum ventral view. Scale bars, Fig. 16: 0.1 mm; Fig. 17: 0.01 mm; Figs 18 – 19: 0.05 mm; Figs 20 – 21: 0.025 mm.

FIGURES 22 – 29. Mature larva of Austrolimnius elatus. 22) thorax and first abdominal segment, dorsal view; 23) tergum of abdominal segment V, showing central and median rows of tubercles and setiferous tubercles on posterior margin; 24) sternum of abdominal segment VII; 25) abdominal segment IX; 26) operculum, ventral view; 27) operculum dorsal view; 28) prothoracic leg; 29) hook of gill chamber. Scale bars: Figs 22, 24 – 28: 0.1 mm; Figs 23, 29: 0.05 mm.