Motonerus
Creators: name: Ek, Martin Fiká Č
name: Short, Andrew Edward Z.
Publisher: name: Zenodo
Year: 2006
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Hydrophilidae
Motonerus

description: Key to the species of Motonerus
1 Preepisternal elevation without median concave area (sometimes the median part can be very slightly concave by an aggregation of coarse superficial punctures), narrow to lamellar (4.0× longer than wide). First abdominal ventrite with or without additional longitudinal ridges parallel to median longitudinal carina. Hind wings present or missing.................................................................................................................................. 2
­ Preepisternal elevation with deep median concave area, 4.0× longer than wide. First abdominal ventrite always with additional ridges parellel to median longitudinal carina. Hind wings present................................................................................................. 8
2 Smaller species (1.5–1.8 mm). First abdominal ventrite without additional longitudinal ridges situated laterally of median longitudinal carina (as in Fig. 62). Elytra evenly, highly convex in lateral view (Figs. 21–22). Preepisternal elevation narrow, 5.0× longer than wide to lamellar (Figs. 32–33). Hind wings missing. Metaventrite without median depression......................................................................................................... 3
­ Larger species (> 1.9 mm). First abdominal ventrite with or without distinct additional longitudinal ridges situated laterally of median longitudinal carina. Elytra evenly convex or distinctly depressed in lateral view (Figs. 23. 24, 27, 30, 31). Preepisternal elevation variably shaped. Hind wings present. Metaventrite with or without median depression...................................................................................................................... 4
3 Prosternal anteromedian excision deep and wide (Fig. 43). Preepisternal elevation in form of narrow plate, 5.0–6.0× longer than wide, ca. as long as metaventrite (Fig. 32), usually slightly narrowing posteriad, bearing coarse irregular punctures. Elytral lateral margins without denticles, or with only fine and very distant denticles basally (Fig. 54). Eyes very small, separated by 16× dorsal width of one eye (Fig. 63) ..................... .............................................................................................................. M. apterus sp. n.
­ Prosternal anteromedian excision shallow, with large tooth situated medially (Fig. 46). Preepisternal elevation nearly lamellar, distinctly longer than metaventrite; carina not very distinct posteriorly (Fig. 33). Elytral lateral margins with distinct and closely standing denticles basally, denticulation reaching elytral apex (Fig. 55). Eyes larger, separated by 10× width of one eye (Fig. 64) ............................... M. oosternoides sp. n.
4 Elytra strongly depressed in lateral view (Fig. 23). Prosternal anteromedian excision
very shallow, rounded, with finely crenulate anterior margin (Fig. 44). Preepisternal elevation lamellar, metaventrite without median depression (Fig. 34) ........................... .......................................................................................................... M. depressus sp. n. ­ Elytra either evenly and highly convex or slightly depressed in lateral view. Prosternal anteromedian excision deeper, more or less rectangular. Preepisternal elevation narrow, but in form of distinct plate. Metaventrite with or without median depression.... 5
5 Elytra evenly convex in lateral view (Fig. 31). Preepisternal elevation very narrow, about 10.0× longer than wide, metaventrite without median depression (Fig. 40). Additional longitudinal ridges present only on abdominal ventrite 1. Denticulation of lateral margins of elytra fine but distinct, nearly reaching elytral apex Motonerus sp. A
­ Elytra differently shaped (Figs. 24, 27, 30). Additional longitudinal ridges present on abdominal ventrites 1 and 2 (as in Fig. 62), sometimes developed also on abdominal ventrite 3. Metaventrite with more or less distinct elongate median depression .......... 6
6 Elytra abruptly elevate immediately behind pronotum, then slightly depressed in lateral view (Fig. 24). Denticles on elytral margin becoming gradually more distant apicad, reaching 0.5 of elytral length (Fig. 57). Preepisternal elevation very long, 6.0× longer than wide (Fig. 37) .................................................................... M.nublado sp. n.
­ Elytra not abruptly elevate behind pronotum in lateral view. Denticles on elytral margin fine, equidistant or nearly so, reaching elytral apex. Preepisternal elevation 3.0–5.0× longer than wide............................................................................................. 7
7 Preepisternal elevation wider, 3.0–4.0× longer than wide, with very indistinct narrow median concave area (Fig. 39) .................................... M. problematicus sp. n. (in part)
­ Preepisternal elevation narrower, 5.5× longer than wide, without median concave area (Fig. 41) ................................................................................................. Motonerus sp. B
8 Preepisternal elevation narrower, 2.2–4.0× longer than wide (Figs. 35, 39). Lateral margins of elytra with denticles reaching elytral apex (as in Fig. 59) .......................... 9
­ Preepisternal elevation wider, 1.6–2.0× longer than wide (Figs. 36, 38). Elytral margins smooth at elytral apex.......................................................................................... 10
9 Elytra highly convex in lateral view (Fig. 25). Preepisternal elevation 2.2–3.0× as long as wide, with very distinct median concave area (Fig. 35). Pronotal punctation slightly coarser and sparser. Abdominal ventrite 2 without or with only indistinct longitudinal ridges, abdominal ventrite 3 lacking these ridges. Median lobe with bottle­neck­like apex (Figs. 13, 14) ............................................................................ M. andersoni sp. n.
­ Elytra distinctly depressed in midlength in lateral view (Fig. 27). Pronotal punctation slightly finer and denser. Preepisternal elevation 3.0–4.0× longer than wide, with indistinctly developed median concave area (Fig. 39). Abdominal ventrites 2 and 3 with slightly developed longitudinal ridges. Median lobe without bottle­neck­like apex (shaped as in Figs. 19–20) .................................. M. problematicus sp. n. (in part)
10 Elytra nearly continuously convex from base to apex in lateral view (Fig. 28). Pronotum sparsely punctate. Elytral costae similarly elevate or only indistinctly alternate in
basal half. Abdominal ventrite 2 without or with only indistinct longitudinal ridges (Fig. 61). Median lobe slightly widened subapically, with small excision on the apex (Figs. 17–18) .................................................................................. M. obscurus Hansen ­ Elytra distinctly flattened in basal third in lateral view (Fig. 26). Pronotum very densely punctate. Elytral costae on intervals 2, 4, 6 and 8 distinctly higher than adjacent ones. Abdominal ventrite 2 with slightly developed longitudinal ridges Median lobe narrowing apicad, with deep excision on apex (Figs. 15–16) ..... M. hanseni sp. n.
description: Published as part of Ek, Martin Fiká Č & Short, Andrew Edward Z., 2006, A revision of the Neotropical genus Motonerus Hansen (Coleoptera: Hydrophilidae: Sphaeridiinae), pp. 1-38 in Zootaxa 1268 on pages 7-9, DOI: 10.5281/zenodo.173209