Echinoaesalus Zelenka, 1993

Paulsen, M. J., 2018, Generic changes in the stag beetle tribe Aesalini (Coleoptera: Lucanidae: Aesalinae) with the description of two new species, Insecta Mundi 666, pp. 1-10 : 2-4

Echinoaesalus Zelenka, 1993

Type species. Aesalus jaechi Zelenka.

The first aesaline from Southeast Asia was described by Krikken (1975). The years 1993 and 1994 were extremely active for species for the region, as Araya (1993), Araya et al. (1993), and Araya et al. (1994) named new species. At the same time, Zelenka (1993) created the subgenus Echinoaesalus to accommodate three species of Aesalus from Southeast Asia, including two new species and A. timidus Krikken. The new genus was differentiated from Aesalus based on the species’ convex form, protibiae with three teeth and lacking other minute serrations, middle and hind legs lacking strong external teeth, and lack of sexual dimorphism in the mandibles. Zelenka (1993) also discussed the presence of weak depressions or complete sulci on the abdomen to receive the hind legs. However, two of the three species he included in Echinoaesalus , including the type species A. jaechi Zelenka ( Fig. 1 ), have the venter more or less unmodified and do not possess complete sulci ( Fig. 2 ). Zelenka (1994) added two more new species and transferred A. hidakai Araya et al. to the genus while removing the presence of ventral depressions or sulci on the abdomen from the generic description (indicating that they could be absent or distinct). Later, Krikken (2008) created the subgenus Zelenkaesalus for A. timidus (type species), E. sabahensis Zelenka ( Fig. 3 ), and one new species, uniting them for their distinctive, complete ventral sulci ( Fig. 4 ). Huang et al. (2011) described three new species from Borneo and Java, and included a key to the twelve species of Echinoaesalus then known. Huang and Chen (2015) described a new species from Taiwan. Huang et al. (2015) described one new Malaysian species and elevated E. borneoensis Huang and Imura to specific status.

Huang and Chen (2017) noted that Echinoaesalus was a composite of three disparate groups based on characters of the vestiture and female genitalia, but they refrained from formalizing these groups due to their inability to study the type species, E. jaechi . Instead they characterized the three groups as the matsuii group, hidakai group, and subgenus Zelenkaesalus . The characters separating these groups are robust and typically used to separate genera within Aesalini ( Table 1 ). For this reason, after examination of detailed images of the Zelenka types in Vienna the three groups can be formally recognized as genera.

Echinoaesalus Zelenka (matsuii group of Huang and Chen 2017) is restricted to the following seven species:

E. arayai Huang and Imura MALAYSIA: Sabah (Borneo)

E. barriesi Zelenka INDONESIA: Sumatra

E. chungi Huang and Chen TAIWAN

E. dharma (Araya et al.) THAILAND

E. jaechi Zelenka INDONESIA: Sulawesi

E. matsuii (Araya) MALAYSIA: Pahang

E. yongi (Araya) MALAYSIA: Selangor

Among Southeast Asian taxa the genus Echinoaesalus can be distinguished easily by the scattered, stick-like bristles on the elytra ( Fig. 1a ; clumps of broad scales are absent). The ventral surface is relatively unmodified and lacks the complete sulci to receive the middle or hindlegs found in Zelenkaesalus . Instead the metasternum has only a short, longitudinal pit laterally (that may receive the tarsi only), and the abdomen is unmodified ( Fig. 1b ). The ocular canthus is long and the eye has a large, ovoid, dorsal portion that cannot be obscured by the pronotum ( Fig. 3 ). The clypeus is more or less triangular but not distinctly acuminate medially ( Fig. 3 ).

Figures

Figures 1–2. Zelenka holotypes. 1) Holotype of Echinoaesalus jaechi Zelenka. a) Dorsal habitus. b) Abdomen, ventral view. c) Labels. 2) Holotype female of Echinoaesalus sabahensis Zelenka. a) Dorsal habitus. b) Abdomen, ventral view, showing complete leg-shaped sulci. c) Labels. Photos courtesy H. Schillhammer (Naturhistorisches Museum, Vienna).

Figures 3–5. Generic differences of ocular canthus/eye and clypeal apex. 3) Echinoaesalus spp. 4) Strabaesalus spp. 5) Zelenkaesalus spp.