Aphelocerus coalitus, OPITZ, 2005

OPITZ, WESTON, 2005, Classification, Natural History, And Evolution Of The Genus Aphelocerus Kirsch (Coleoptera: Cleridae: Clerinae), Bulletin of the American Museum of Natural History 2005 (293), pp. 1-128 : 17-18

DIAGNOSIS OF APHELOCERUS

One of the most interesting, but difficult to find, generic characteristic of these beetles is the presence of an elytral trich, an extraordinarily elongated seta near the apex of each elytron (fig. 257). Superficially, however, most of these beetles are conveniently recognized by their shiny black integument and the presence of a streak of silvery setae at the base of the sutural margin and/or on the elytral disc. Only in specimens of A. coalitus , n.sp., A. delicatulus Barr , A. affaniatis , n.sp., and sometimes in specimens of A. inconstans Gorham , is the dorsum partially rufous or variously testaceous. Specimens of Aphelocerus have the pronotum consistently narrower than the width of the elytra across the humeri. Further, the members of most of the species show a tuft of silvery setae at the middle of the elytral disc that is usually divided into two variously developed setal patches (anterior patch and posterior patch) that in aggregate are usually proximal to the sutural margin (see frontispiece).

The integumental pubescense, particularly those found on the frons, pronotum, and el­ ytra, are identified as primary (18) or secondary (28) setae. The primary setae (fig. 260) are usually more robust, more vertical, and not aggregated into groups whereas the secondary setae (fig. 258) are slender, shorter, more decumbent, and arranged into one, two, or three patches that combine to give the appearance of a single setal tuft.

The assignment of specimens to species is very difficult. Variations in aedeagal characteristics provide the most reliable criteria for species­level identifications. One particularly dramatic exception to interspecific aedeagal diversity is the virtually identical shape of the aedeagus in males of A. echinatus , n.sp. (fig. 144b), and A. affaniatis , n.sp. (fig. 144a). What makes this aedeagal similarity extraordinary is the extent to which the members of these species differ externally.

For identification of specimens of Aphelocerus to species level, the aedeagus of all available males should be examined. Other attributes used to discriminate the species are length of the antenna and the shape of its club, presence or absence of white setal tufts on the frons and lower side margins of the pronotum, size and shape and number of setal patches of the elytral middiscal setal tuft and the direction of their seta, pronotal shape, width of the pronotum in relation to the width of the elytra across the humeri, degree of angularity of the epipleural margin in the posterior fourth of the elytra, convexity of the posterior half of the elytra, length of the metatibia, and shape of the pygidium and sixth visible abdominal sternum. Aphelocer­ an specimens from whom elytral discal setae have been abraded may be difficult to identify, but the minute punctations from which the tuft setae arise give an indication of the presence and shape of the tuft. In a few cases geographic distribution was used as a convenient characteristic to assign externally similar specimens to species.