Epimetopus mendeli, Fikáček & Barclay & Perkins & Sw, 2011

Fikáček, Martin, Barclay, Maxwell V. L., Perkins, Philip D. & Sw, London, 2011, Two new species of the Epimetopus mendeli species group and notes on its adult and larval morphology (Coleoptera: Hydrophiloidea: Epimetopidae), Acta Entomologica Musei Nationalis Pragae 51 (2), pp. 477-504 : 480

Epimetopus mendeli species group

All three members of this species group can be easily distinguished from all other described species of Epimetopus by the combination of the following characters:

1. eyes incompletely divided into dorsal and ventral portion: anterior ocular canthus present, posterior canthus absent [both anterior and posterior canthi are developed and meet each other in many other Epimetopus species , hence their eyes are completely divided into dorsal and ventral halves; both canthi are reduced in an unidentified species from KSEM examined during this study];

2. median lobe of the aedeagus complex, bearing lateral projections ( Figs. 3–5 , lap) in the basal portion, and two pairs on the apex – longer ventral ones ( Figs. 26–29 , vl) and shorter dorsal ones ( Figs. 26–29 , dl) [in contrast, the median lobe is simple in all other described Epimetopus species , lacking lateral projections at the base and not apically subdivided into two pairs of lobes];

3. elytra with alternating ridge-like and flat intervals, flat intervals without series of elongate tubercles [elytral intervals between elytral ridges bear serially arranged elongate tubercles in several other Epimetopus species ];

4. body large, more than 2.2 mm long, and general body coloration dark brown [this distinguishes the species treated here from the species of the E. costatus group which also have eyes incompletely divided by a canthus, but are characterized by a small, rufescent body].

Based on the combination of these characters, it seems probable that the three species treated in this paper form a monophyletic group. Although this requires testing by a phylogenetic analysis in the future, we here formally define the group as the ‘ Epimetopus mendeli species group’ in order to facilitate orientation within the genus prior to a complete taxonomic and phylogenetic revision.

All three species included in the E. mendeli species group are very similar in external characters, and can only be reliably distinguished by the morphology of the aedeagus.

Figures

Figs. 1–5. General habitus and aedeagi of Epimetopus. 1–2 – E. mendeli sp. nov., general habitus (body length 3.4 mm): 1 – dorsal view; 2 – lateral view. 3–5 – aedeagus of the holotype: 3 – E. mendeli sp. nov., 4 – E. flavicaptus sp. nov., 5 – E. angulatus Balfour-Browne, 1949. Abbreviations: lap – lateral process of median lobe.

Figs. 26–29. Details of the aedeagal morphology. 26–27 – Epimetopus mendeli sp. nov., paratype from the type locality: 26 – ventral view; 27 – dorsal view. 28–29 – E. flavicaptus sp. nov., holotype:28 – ventral view; 29 – dorsal view. Abbreviations: dl – dorsal lobe; vl – ventral lobe.