Pretarsus and distal margin of the terminal tarsomere as an unexplored character system for higher‐level classification in Cholevinae (Coleoptera, Leiodidae)

Abstract

Cholevinae are well founded as a monophylum, but their internal phylogenetic relationships constitute a matter of longstanding dispute. The morphology has been the main source of information in most available phylogenetic studies on the subfamily. Most of the characters used, however, were limited to easily visible external structures and genitalia. Here we investigate the informative power of an unexplored character system for the higher-level systematics of Cholevinae: the morphology of the pretarsus and distal margin of the terminal tarsomere. We analysed and documented these structures in representatives of the five most species-rich tribes of Cholevinae (encompassing 13 subtribes) using scanning electron microscopy. We identified several diagnostic features and recognize potential synapomorphies at the tribal, subtribal and generic levels. The architecture of the median and empodial sclerites (including the empodial setae), the shape and composition of the medial projection of the distal margin of the terminal tarsomere, and the armature of the claws were considered a promising source of information for delimiting tribes and subtribes. Our data challenge the traditional view of a close proximity of Eucatopini and Ptomaphagini as well as a previously suggested synapomorphy of Leptodirini, and reinforce the monophyly of Ptomaphagini. This contribution is one of the rare comparative studies on the coleopteran pretarsus and one of very few evaluating the systematic usefulness of the distal margin of the terminal tarsomere in insects. 392

Morphology‐based phylogenetic reconstruction of Cholevinae (Coleoptera: Leiodidae): a new view on higher‐level relationships

“… Medial projection of terminal protarsomere (modified from Antunes‐Carvalho and Gnaspini, : Ch1): (0) weakly developed (Fig. a); (1) trapezoidal/triangular (e.g., Fig.…”

“…(c) Dellabeffaella roccae (Leptodirini). mpp, paired medial projections of the terminal tarsomere; rsmp, oblique row of spines on the medial projection of the terminal tarsomere. Oblique row of spines (rsmp) of medial projection of terminal protarsomere (Antunes‐Carvalho and Gnaspini, : Ch2): (0) absent (e.g., Fig. a, c); (1) present (Fig.…”

“…The spines are arranged as a cluster in some of these taxa, but more commonly in a row. They are lacking in Leptodirini and Sciaphyini. Medial projection of terminal meso‐ and metatarsomere (modified from Antunes‐Carvalho and Gnaspini, : Ch1): (0) weakly developed; (1) trapezoidal/triangular; (2) paired (mpp). The shape of the ventral margin of the terminal meso‐ and metatarsomere is generally similar to that of the protarsomere, with a few exceptions: the medial projection of the meso‐ and metatarsomere is paired in Eucatops sp.…”

“…(, ). Terms related to the morphology of the pretarsus and distal margin of the terminal tarsomere follow Antunes‐Carvalho and Gnaspini ().…”

Cave hygropetric beetles and their feeding behaviour, a comparative study of Cansiliella servadeii AND Hadesia asamo (Coleoptera, Leiodidae, Cholevinae, Leptodirini)

“…However, they have been observed neither in Cansiliella (Paoletti et al 2013: Fig. 2b), nor in other tribes of Cholevinae for which the structure of tarsi have been investigated in detail (Antunes-Carvalho & Gnaspini 2015). The true function of the bristles has not yet been verified and must be tested.…”