Leptostylus LeConte, 1852

Nascimento, Francisco E. De L. & Heffern, Daniel, 2018, New species of Acanthocinini Blanchard, 1845 (Coleoptera, Cerambycidae) from Rondônia state, Brazil and notes on some genera, Zootaxa 4446 (2), pp. 292-300 : 293

Leptostylus LeConte, 1852

Leptostylus LeConte, 1852: 168 ; Monné, 2018: 75 (cat.).

The definition of Leptostylus is controversial and the differentiation from Leptostylopsis Dillon, 1956 seems somewhat arbitrary. Firstly, when proposing Leptostylus, LeConte (1852: 168) reported: “the thorax is tuberculous on the disc, and more or less prominent on the sides; the elytra are very slightly truncate at the tip.” Subsequently, when proposing Leptostylopsis, Dillon (1956a) pointed out: “from Leptostylus , this genus differs in the less strongly tuberculate pronotal disk, and the longer antennae with the fifth and sixth segments much longer… and the mesosternal process is broader, exceeding, as a rule, a mesocoxal cavity in width”. In the same work, Dillon (1956a) pointed out about Leptostylus : “The chief characteristics of this genus are the strongly tuberculate disks of pronotum and elytra, the lateral tubercle of the former placed only very indistinctly behind the middle, the elytral basal gibbosity prominent, the antennal scape rather short, reaching only slightly behind pronotal lateral tubercles, fifth segment one-half or two-thirds length of first, and sixth segment less than half as long as first. In addition, the shape of the front, the characters of the pro- and mesosternal processes, and the length of first tarsal segment are diagnostic”.

Linsley & Chemsak (1995) used almost the same characteristics to define Leptostylus : “This genus may be recognized by the convex body form, prominent dorsal tubercles of the pronotum, relatively short antennae, width of the sternal processes, and by the basally gibbose, costate elytra with numerous tufted tubercles”.

Apparently, the pronotal tubercles, shape of the scape, antennal length, and the proportions of the antennomeres V–VI, do not separate these genera, or at least, several species are erroneously inserted into these genera. For example, by examining the photo of Leptostylus latifasciatus Zayas 1975 , there are no prominent tubercles on pronotal disk or at base of the elytra; Leptostylus neivai Melzer, 1930 , does not have tubercles on pronotum or at sides of the prothorax; and Leptostylopsis viridicomus (Fisher, 1942) has remarkably elevated tubercles on the pronotum. In the key to the species of Leptostylus, Monné & Hoffman (1981) reported (translated): “3(1) pronotum without tubercles or slightly prominent elevations”; “8(7) elytral apex rounded.” Both of these features do not agree with the original description of Leptostylus . In other words, there are species in both genera that do not agree with the original description or any prior generic definitions of Leptostylus and Leptostylopsis .

When studying the species deposited at MZSP, we did not find reliable characteristics to separate these genera and a meticulous review is necessary. For now, due to the scarcity of material, we only mention the need to study this group in depth.