A new species of Ischyomius from Venezuela ( Coleoptera , Tenebrionoidea , Pythidae ) with a revised key to world species

A new species – Ischyomius escalonai – is described from Venezuela (type locality: Lara, Yacumbú National Park, El Blanquito). Males of I. escalonai have distinctive genitalia with very short accessory lobes, and both sexes have simple elytral apices, without the spine that is present in almost all other species of the genus. Th e type specimens of I. escalonai were collected in association with dry leaves of Bird of Paradise (Strelitzia sp.) plants. A revised key to species of Ischyomius is provided.


Introduction
As outlined by Pollock (1998Pollock ( , 2007)), the genus Ischyomius has been, until recently, an enigma within the superfamily Tenebrionoidea.After historical placements in Tenebrionidae, Melandryidae, Tetratomidae and Trictenotomidae, the genus now has a solid placement within Pythidae.A preliminary study of the putative larva of Ischyomius further confi rms its placement in Pythidae (Pollock, unpublished).Pollock (1998) tentatively placed the genus near the monotypic Sphalma Horn, based on shared possession of concealed antennal insertions, very large mandibular mola, and lateral pronotal carinae.
Th e description of species of Ischyomius has a "bimodal" distribution; after description of the fi rst four species from 1878 to 1916 (Chevrolat 1878;Champion 1916), it was another 90 years until the next two species were described (Pollock 1998).Th en, based on recently collected material, a seventh species -I.hovoreiwas described by Pollock (2007).With the present description of I. escalonai, sp.n., the diversity of Ischyomius is now comparable to that of Pytho Latreille, the latter of which has 9 described species.It seems likely that additional new species will be discovered, thus making it the most diverse genus in the family.All other pythid genera comprise one or two species only.
Derivation of specifi c epithet.I am very pleased to name this new species after friend and colleague Hermes Escalona, a fellow specialist on the "salpingid group" of tenebrionoid families, and who also collected all known specimens of this species.
Diagnosis.Th is new species of Ischyomius may be separated from the rest of the genus by the following combination of characters: posterior pronotal bead indistinct; lateral pronotal bead not attaining anterior bead; color uniformly light to medium brown; abdominal ventrites with short but obvious setation; elytral apices rounded, without spine (Fig. 3) aedeagus relatively short and stout, accessory lobes very short, inserted midlength on the tegmen (Fig. 4); known only from Venezuela.
Distribution.Th e four type specimens were collected from a single locality, in Yacambú National Park, Lara State, in easternmost Venezuela.
Natural history.All four specimens were collected by beating withered leaves of "Bird of Paradise" plants (Strelitzia sp.) (Hermes Escalona, pers.comm.).Very little is known about any other species of Ischyomius, although they seem to be associated with dead or dying vegetation of Musaceae or Palmae (Champion 1916;Pollock 1998).Although the genus Strelitzia is native to South Africa, and therefore was introduced to the Venezuelan type locality, the family Strelitziaceae is closely related to Musaceae (which are also introduced), in the "banana and ginger" group of plants (Kress and Hahn 1997).It seems probable that I. escalonai will be found in association with Musaceae, also.
Discussion.Th e description of I. escalonai brings the total known species in Ischyomius to eight.Th e fi rst couplet of Pollock's (1998) key divided the species into two groups: those that have a distinct, posterior pronotal bead and distinct vestiture on abdominal ventrites and those without posterior bead and lacking ventral abdominal vestiture.Each of the four type specimens of I. escalonai are intermediate between these two groups, i.e. without the pronotal bead, but with short, but distinct ventral abdominal vestiture.Th erefore, the original key of Pollock (1998), revised by Pollock (2007) for inclusion of I. hovorei, must be amended, as follows.References to fi gures for species other than I. escalonai refer to fi gures in Pollock (1998).