Subgenus Choleropsis Franz

Choleropsis Franz, 1975: 291 (as subgenus of Scydmaenus). Type species: Heterognathus geniculatus King, 1864: 98 (monotypy), misidentified as Heterognathus gracilis King, 1864: 97 (ICZN Article 70.3.2; see explanation below).

Misidentified type species. Franz (1975: 291) proposed Choleropsis as a new subgenus of Scydmaenus to accommodate species with male antennomeres 9 and 10 conspicuously modified, the metaventrite in males impressed along midline, fore tarsi in males broadened, and the pronotum with antebasal pits. These characters, except for the modified antennae, are also used to distinguish Choleropsis from Cholerus in the identification key to subgenera of Scydmaenus in the same paper (Franz 1975: 274). Franz (1975) attributed this set of characters to Scydmaenus gracilis (King, 1864) (originally Heterognathus gracilis), which is also redescribed in Franz (1975: 292) as having all of these features. The type material of Heterognathus gracilis examined during the present study includes males which do not have a single diagnostic character listed by Franz for Choleropsis: they have unmodified antennal clubs, fore tarsi not broadened, metaventrites lacking any trace of a median impression, and the pronota lacking antebasal pits. Their aedeagi also differ from that illustrated by Franz (1975: fig. 273) for ‘ Scydmaenus gracilis ’. Moreover, King (1864: 97) does not mention any antennal modifications in his original description of Heterognathus gracilis, while he described such modifications for Heterognathus geniculatus King, 1864, and for Heterognathus princeps King, 1864 . The Franz’s description of the antennomere 10 in male of his ‘ Scydmaenus gracilis ’ as “tief ausgehölt” (deeply excavated) in a combination with the sketch of the aedeagus in lateral view unambiguously proves that the species redescribed by Franz (1975) under the name S. gracilis is in fact Heterognathus geniculatus King, 1864: 98 .

The case of misidentified type species is ruled by ICZN 70.3: “If an author discovers that a type species was misidentified, that author may select, and thereby fix as type species (...) either: 70.3.1 the nominal species previously cited as type species, or 70.3.2 the taxonomic species actually involved in the misidentification.” The ICZN 70.3.2 is applied here to select Heterognathus geniculatus King, 1864: 98 (misidentified as Heterognathus gracilis King, 1864: 97 by Franz, 1975: 292) as the type species of Choleropsis .

Placement of Heterognathus gracilis King, 1864: 97 . This species, placed in Scydmaenus (Cholerus) by Csiki (1919: 73), is here placed in Scydmaenus incertae sedis, based on examination of the following specimens:

Lectotype (here designated; AUSTRALIA: NEW SOUTH WALES): ♂ (Fig. 4), with labels illustrated in Fig. 189: “K23216” [brownish, handwritten], “ Heterognathus / gracilis King / Paramatta, N.S.W.” [white, handwritten], “K 197794” [white, printed], “ SYNTYPE ” [yellow, printed]; white printed LECTOTYPUS label was added during present study (AMS). Paralectotypes (3 exx.): ♂, “K 197789” [white, printed], “ Heterognathus / gracilis King / Paramatta, N.S.W.” [white, handwritten] (AMS); 1 ex. of unknown sex, “K 352152” [white, printed] (AMS); 2 exx. of unknown sex mounted on one cardboard, “ Het. gracilis / 3” [brownish, handwritten], “K 197788” [white, printed], [white, handwritten] (AMS).

Additional material studied (specimens identified as S. gracilis by Lea and later authors, but their true identity remains uncertain; they were studied to verify whether some of them might be syntypes of Heterognathus gracilis; see Remarks below). NEW SOUTH WALES: 2 ♀♀, Glenn Innes and Tweed River, leg. Lea (two specimens on one pin and bearing Lea’s “COTYPUS” label, but localities do not agree with those mentioned by King (1864)) (SAMA); 1 ex. (with crushed head, dissected by Franz, with only a part of abdomen in Euparal preparation, without antennae and aedeagus), most likely originally mounted and pinned together with the ‘cotypus’, with copied labels “Glenn Innes” and “Cotype” (SAMA); 3 exx., each on separate card but on one pin, Glenn Ines, S.W. Lea (SAMA); 1 ex., Forest Reefs, Lea (SAMA); QUEENSLAND: 1 ex., N Queensland, Blackburn’s collection (SAMA). Additionally, 1 ex. with clearly mixed and contradicting labels, presumably coming from different specimens: one typical Lea’s label with “N. S. Wales”, the other one with “N Queensland, Blackb’s Coll.” (SAMA).

Remarks. The lectotype male of S. gracilis is not only externally unremarkable (Fig. 4), showing no peculiar characters, including lack of any secondary sexual features, but also its aedeagus (Figs 5–6) is simple and extremely similar to aedeagi of several Australian and many non-Australian species placed mainly in Scydmaenus s. str. or incertae sedis. The head (Fig. 1) of this species is subrectangular, the submentum lacks lateral lobes (Fig. 2), the antennae in males (Fig. 4) are unmodified, slender, with antennomeres 7 and 8 each distinctly asymmetrical and 9–11 forming distinctly delimited club; the pronotum (Fig. 1) lacks antebasal pits; the basisternal region of prosternum (Fig. 2) is much longer than procoxal rests, the elytra (Fig. 1) lack basal foveae, the mesoventral intermesocoxal process (Fig. 3) is broad subrectangular with parallel lateral margins, posteriorly touching equally broad, short anterior metaventral process; metanepisterna (Fig. 3) are completely demarcated from the metaventrite, and the metaventral intermetacoxal process is broad, short, with its posterior margin nearly straight and posterolateral regions forming subtriangular lobes projecting posteriorly.

As the status of most subgenera remains unclear, and Scydmaenus requires a profound reclassification, I refrain from placing S. gracilis in any subgenus, even though it shows similarities to Scydmaenus s. str., Cholerus (especially females), and some other subgenera characterized by fully demarcated metanepisterna. In the type species of the most similar Scydmaenus s. str. the posterior tentorial pits are situated on a broad and short elevated ‘platform’, the pronotum bears two pairs of antebasal pits, each elytron bears two distinct basal foveae, and the protarsi in males are strongly broadened and bearing tenent setae (Jałoszyński 2016a). All these features are lacking in S. gracilis, and this species cannot be placed in Scydmaenus s. str.

The ‘generalized’ external morphology and the simple, unremarkable aedeagus make it difficult to unambiguously identify S. gracilis . All specimens listed above as additional material studied were identified by Lea and later authors. Franz might have copied Lea’s identification labels from one ‘identified’ specimen placed in a unit tray together with others to put a label on all studied specimens, and this way he probably increased the number of dubious identifications. These specimens are similar to the type series of S. gracilis, but I did not make attempts to verify their identity (some of them are females, some have been partly damaged during previous authors’ dissections, others are in fragile condition). They are listed here to provide a complete documentation of material seen during the present study. More importantly, they were studied to verify whether some of them might be a part of the type series, as some bear “cotype” labels. They were found to be non-types, and as S. gracilis is not the type species of Choleropsis, a detailed redescription of this species remains beyond the focus of the present study. If in future, the remaining species of the Australian Scydmaenus, not included in the present work, are revised, the “additional studied material” listed here should be carefully re-examined, as some of the species described by Franz (1975) as new in Scydmaenus s. str. seem to have similar aedeagi to that of the true S. gracilis, and may even be conspecific. The data provided here can facilitate future verification of Franz’s identifications.

The previously described species that are herein included in Choleropsis were originally described either as Heterognathus by King (1864) and transferred to Cholerus by Csiki (1919), or described by Franz (1975) and originally placed in Cholerus. Their systematics was a conundrum because some of the Franz’s redescriptions and illustrations do not agree with those given by King. During the present study it was found that the type series, or what Franz believed were the type series of some species, are heterogenous, and some specimens (syntypes or non-types) used by Franz for his redescriptions were misidentified. During the present study it was necessary to exclude many specimens from the type series, as they were found not conspecific with syntypes whose characters agree with the original descriptions. Details are given in Remarks for each species.

Diagnosis of Choleropsis . Franz (1975) defined Choleropsis as having: (1) trimerous antennal clubs with antennomeres 9 and 10 asymmetrically modified in males (Figs 58–69); (2) the pronotum with antebasal pits (Fig. 7); (3) the metaventrite in males impressed along midline (Figs 70–75); and (4) protarsi in males slightly broadened (Fig. 12). This combination of characters is confirmed herein as unambiguously differentiating Scydmaenus geniculatus (King) and similar species from all remaining subgenera of Scydmaenus . The diagnosis is here supplemented with nine more characters: (5) the submentum lacking lateral lobes (Fig. 8); (6) the basisternal region of the prosternum subequal in length to procoxal rests and with a long anterior ‘collar’ (Fig. 8); (7) elytra lacking basal foveae (Fig. 7); (8) the mesoventral intermesocoxal process broad and subrectangular (not carinate), posteriorly touching the equally broad anterior metaventral process (Fig. 11); (9) metanepisterna completely demarcated from the metaventrite (Fig. 11); (10) the metaventral intermetacoxal process short and broad, with posterolateral subtriangular lobes projecting posteriorly, as broad as about 1/3 of the metaventral width at the posterior margin, distinctly broader than metacoxa (Fig. 11); (11) the apex of mesotibia in male with a long and curved ventral penicillus composed of several setae (presumable autapomorphy; Figs 13–14); (12) the mesotarsomere 1 in both sexes strongly elongate, about as long as tarsomeres 2–4 combined (Fig. 14); and (13) the aedeagus with its distal region demarcated by a deep dorsal constriction, but not constricted laterally in dorsal view, bearing membranous lateral subapical lobes, lacking setae or with extremely short dorsal setae near the apex (e.g., Figs 16–19).

Composition and distribution. The subgenus Choleropsis is endemic to Australia and includes six species, of which three were previously placed in Cholerus, and one in Scydmaenus s. str.: S. beechmonti Franz, S. geniculatus (King), S. kurandae Franz, S. princeps (King), S. curviclavatus sp. n., and S. kroombitanus sp. n.

Species of Choleropsis can be identified using the following key (females are unremarkable and cannot be identified, unless collected in association with males):