Parascydmus Casey, 1897

Jałoszyński, Paweł, 2019, Notes on Nearctic genera Catalinus Casey and Parascydmus Casey (Coleoptera: Staphylinidae: Scydmaeninae), Zootaxa 4603 (1), pp. 145-158 : 151-157

Genus Parascydmus Casey

Parascydmus Casey, 1897: 473 (as subgenus of Scydmaenus sensu Thomson (1859) (= Stenichnus )). Type species: Scydmaenus corpusculum Casey, 1897 (des. Franz (1985)). Elevated to genus rank by Franz (1985).

Revised diagnosis. Body stout, with distinct constrictions between head and pronotum and between pronotum and elytra; head and prothorax lacking thick bristles; head subtriangular with conspicuously long and broad clypeus; vertex not bulging posterodorsad; eyes located in posterior portion of head; mandible subtriangular, with one mesal preapical tooth; antennae gradually thickened; lateral sutures of submentum present, their posterior ends nearly meet at middle; hypomeral ridges complete; posterior tentorial pits hidden in transverse groove demarcating ventrally ‘neck’ region; occipital constriction only slightly narrower than vertex; pronotum broadest distinctly in front of middle, with sharp lateral marginal carinae in posterior third, and with three pairs of antebasal pits, lacking sublateral carinae and transverse groove; procoxal cavities closed; prosternal process narrowly carinate, sharply marked, weakly elevated, hidden between procoxae; basisternal part of prosternum much shorter than coxal part; hypomeral ridges absent; notosternal sutures complete; mesoventrite with asetose procoxal rests, deep setose impressions behind the asetose area and carinate mesoventral intercoxal process extending posteriorly to middle of mesocoxae; anterior metaventral process indistinct, diffuse; metacoxae subcontiguous, i.e., narrowly separated by short metaventral intercoxal process with deep median notch dividing it into a pair of long, pointed lateral spines; each elytron with one vestigial asetose basal fovea near suture; mesoscutellum not exposed; aedeagus with asymmetrical median lobe broadening from narrow base, lacking endophallic sclerites and lacking parameres.

Redescription. Body ( Fig. 8 ) elongate and relatively stout, strongly convex, with deep constrictions between head and pronotum and between pronotum and elytra, brown and covered with setae, without thick bristles, adult body length of the type species 1.15 mm.

Head capsule ( Figs 9–10 ) with anterior part (in front of occiput) subtriangular in shape. Occipital constriction slightly narrower than vertex; tempora much shorter than eyes, rounded; vertex transverse and posteriorly convex, lacking posterior ridge, not bulging posterodorsad, anteriorly demarcated from frons by a diffuse transverse impression; frons subtrapezoidal and anteriorly narrowing, with a pair of deep supraantennal notches; frontoclypeal groove present, short; clypeus conspicuously long and broad, its anterior margin broadly rounded; supraantennal tubercles weakly elevated; antennal insertions broadly separated. Eyes large, coarsely faceted, weakly projecting from the silhouette of the head.

Gular plate ( Fig. 10 ; gp) large and subtriangular; gular sutures ( Fig. 10 ; gs) distinct; posterior tentorial pits not exposed, hidden in a transverse groove demarcating ‘neck’ region ventrally.

Labrum transverse with anterior margin arcuate. Mandibles ( Fig. 10 ) only partly visible in available specimens, symmetrical, each subtriangular, with one small mesal preapical tooth ( Fig. 10 ; mt). Maxilla ( Fig. 10 ) generalized, as in all genera of Glandulariini , with moderately long maxillary palp composed of minute and distinctly elongate palpomere I, strongly elongate, pedunculate palpomere II, broad palpomere III broadest near distal third, and strongly elongate and slender subconical and pointed palpomere IV longer than half length of palpomere III. Labium ( Fig. 10 ) with triangular submentum ( Fig. 10 ; smn) demarcated laterally from postcardinal regions by lateral sutures ( Fig. 10 ; lss) which are strongly convergent posteriorly and their ends nearly meet in front of gular plate; mentum ( Fig. 10 ; mn) subtrapezoidal, transverse; prementum short, bearing labial palps with all palpomeres distinctly elongate (palpomere II the longest); anteromedian region of prementum not exposed in studied specimens. Hypostomal ridges ( Fig. 10 ; hr) distinct and complete, extending posteromesally and connected at the junction of lateral sutures of submentum.

Antennae ( Fig. 8 ) moderately slender, distinctly and gradually thickened toward apices.

Pronotum ( Figs 8–9 ) in dorsal view approximately bell-shaped, not elongate, broadest slightly in front of middle; anterior margin arcuate and laterally confluent with sides of pronotum without any indication of anterior corners; lateral margins rounded in anterior half and slightly concave near posterior third; posterior corners distinct, nearly right; posterior margin very shallowly bisinuate. Pronotum with three pairs of lateral antebasal pits ( Fig. 9 ; abp); lateral marginal carinae ( Fig. 9 ; lc) sharply marked in posterior third; sublateral carinae and transverse groove absent.

Prosternum ( Fig. 10 ) with basisternal part ( Fig. 10 ; bst) much shorter than coxal part (but not vestigial) and distinctly demarcated from procoxal cavities; median portion of sternum with weakly elevated and sharply marked narrow longitudinal carina, in intact specimens hidden between procoxae ( Fig. 10 ); procoxal sockets presumably closed; notosternal sutures ( Fig. 10 ; nss) visible on entire length; hypomeral ridges absent.

Mesoscutellar shield not visible between elytral bases in intact beetle.

Mesoventrite ( Fig. 11 ) with narrow anterior ridge ( Fig. 10 ; ar); large, asetose transverse area partly divided at middle and functioning as a procoxal rest ( Fig. 11 ; pcr), and behind it with a pair of large, transverse setose impressions separated by a carinate mesoventral intercoxal process ( Fig. 11 ; msvp), the latter moderately elevated (not keel-like), posteriorly reaching middle of mesocoxae, with a distinct posterior tip.

Metanotum not studied.

Metaventrite ( Fig. 11 ) subtrapezoidal, distinctly broadening posteriorly, with diffuse and indistinct anterior metaventral process; metaventral intercoxal process ( Fig. 11 ; mtvp) narrow, subtrapezoidal, with a deep median notch dividing it into a pair of long and pointed spines. Metanepisterna and metepimera narrow.

Metendosternite (= metafurca) not studied.

Elytra ( Figs 8–9 ) oval, with distinct, elongate humeral calli and with shallow basal impressions, each with one vestigial asetose basal fovea ( Fig. 9 ; bef), apices separately rounded.

Hind wings not studied.

Legs ( Figs 8 , 10–11 ) long and slender; pro- and mesocoxae in ventral view oval, metacoxae strongly transverse, laterally reaching lateral margins of metaventrite; all trochanters short, subtriangular; all femora weakly and gradually clavate; tibiae straight or nearly so; tarsi moderately long and slender.

Abdominal sternites unmodified.

Aedeagus ( Figs 12–13 ) unusual in shape and structure, with slightly asymmetrical median lobe narrowest at base and strongly broadened distad, basal portion developed as a slender tubular ‘stalk’ curved dorsad, endophallus lacking sclerites; parameres absent.

Composition. 4 species.

Distribution. North America ( Canada: Ontario; USA: Massachusetts, Pennsylvania).

Remarks. Specimens that are included in the type series were syntypes until Franz (1985). One of them had been labeled as holotype and others as paratypes before Franz studied them, but as he mentioned, this was incorrect ( Franz 1985). Franz designated one of the specimens as ‘holotype’ (specimen in Fig. 8 with labels shown in Fig. 14 ), also in error. However, ICZN allows for such a specimen to become a correctly designated lectotype, if certain re- quirements are met. Franz (1985) provided data to unambiguously identify his selected specimen (the only dissected male whose aedeagus he illustrated), but he did not explicitly state that the designated specimen was to serve as the name-bearing type. The latter is a requirement of ICZN 74.5 for a specimen referred to as holotype (in error) to have been correctly designated as lectotype. Yet there is no reason why Franz would have designated a holotype, other than for the selected specimen to serve as the name-bearing type; this function is strictly attributed to the holotype. I here interpret the use of the word “ holotype ” as an explicit indication that the specimen selected by Franz (1985) was to serve as a name-bearing type, and consequently the Franz’s action was a valid lectotype designation.

Franz’s (1985) remark that Parascydmus differs from Neuraphes in the lateral pronotal carinae absent or vestigial in the former genus and present in the latter is misleading. The lateral carinae in P. corpusculum are fairly distinct and sharply marked, although restricted to the posterior third of pronotum. There are other, more distinct morphological differences between these genera, listed above. In a preliminary phylogenetic analysis of Glandulariini , Parascydmus takes place as a sister genus to the Japanese Rutaraphes (Jałoszyński, unpublished). These two genera share most characters, including the unique, deep supraantennal notches in the anterolateral margins of frons, and the aedeagus lacking parameres (although the presence of an inner apodeme in Parascydmus , lacking in Rutaraphes , constitutes an important difference). They even have the frons modified, although in a slightly different way (see Jałoszyński (2015)). In future these genera may require merging into one, although a discovery of more species (and a detailed morphological review of all species of Parascydmus ) would help solving this interesting biogeographic and taxonomic problem.

Conclusions. Parascydmus is here maintained as a separate genus. It is defined only by a combination of synapomorphies known to occur in other glandulariines, but this set of features is unique and allows for unambiguous identification. However, in future this genus and Rutaraphes may be merged; see the previous paragraph.

Comparative notes. Parascydmus belongs to a group of genera characterized by the submentum demarcated laterally by sutures. This group includes 19 other genera; Parascydmus differs from each of them in the following characters:

- from Alloraphes in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Alloraphes ); the lateral sutures of submentum meeting posteriorly (broadly separated in Alloraphes ); the sides of pronotum lacking thick bristles and the pronotal base without the antebasal transverse groove (bristles and groove present in Alloraphes ); the hypomeral ridges absent (present in Alloraphes ); the metaventral intercoxal process with a pair of long and pointed lateral spines (shallowly notched at middle in Alloraphes ); the aedeagus lacking parameres and lacking the basal pumping apparatus (both present in Allor- aphes);

- from Austrostenichnus in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Austrostenichnus ); the prosternal process present, weakly elevated but sharply defined (absent in Austrostenichnus ); the pronotum lacking a transverse groove (present in Austrostenichnus ); the mesoventrite with a carinate mesoventral intercoxal process (absent in Austrostenichnus ); the aedeagus lacking parameres (present in Austrostenichnus );

- from Delius in the head and prothorax lacking thick bristles (present in Delius ); the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Delius ); the basisternal part of prosternum much shorter than coxal part (subequal in length in Delius ); the mesoscutellum not exposed between elytral bases (in Delius exposed); metacoxae laterally reaching lateral margins of metaventrite (broadly separated from sides of metaventrite in Delius ); the aedeagus lacking parameres (present in Delius );

- from Catalinus in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Catalinus ); the lateral sutures of submentum posteriorly nearly meeting (broadly separated in Catalinus ); the prothorax with lateral carinae and antebasal pits (absent in Catalinus ); the metaventral intercoxal process with a pair of pointed lateral spines (with a pair of short lateral subtriangular, blunt projections in Catalinus ); the aedeagus broadest in distal half, lacking parameres and lacking endophallic sclerites (broadest in basal half, presumably with parameres and with long endophallic sclerites in Catalinus );

- from Leptoderoides in the head and prothorax lacking thick bristles (present in Leptoderoides ); the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Leptoderoides ); the pronotum lacking sublateral carinae (present in Leptoderoides ); the hypomeral ridges absent (complete in Leptoderoides ); the aedeagus lacking parameres (present in Leptoderoides );

- from Madagaphes in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Madagaphes ); the lateral sutures of submentum nearly meeting posteriorly (broadly separated in Madagaphes ); the pronotum with lateral carinae (absent in Madagaphes ); an indistinct, diffuse prosternal intercoxal process (carinate, sharply marked in Madagaphes ); the hypomeral ridges absent (in Mada- gaphes present, although their anterior and posterior portions obliterated); the metaventral intercoxal process with a pair of long pointed spines (lacking spines in Madagaphes ); the mesoscutellum not exposed between elytral bases (in Madagaphes exposed); the aedeagus lacking parameres (present in Madagaphes );

- from Mexiconnus in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Mexiconnus ); the pronotum lacking the antebasal groove (present in Mexiconnus ); the hypostomal ridges complete, posteriorly reaching posterior tentorial pits (incomplete, posteriorly obliterated in Mexiconnus ); the hypomeral ridges absent (complete in Mexiconnus ); the prothorax lacking thick bristles (present in Mexiconnus ); the basisternal part of prosternum much shorter than the coxal part (subequal in length in Mexiconnus ); the protarsi in male unmodified (strongly broadened at base and with conspicuously long and dense ventral setae in Mexiconnus ); the aedeagus lacking parameres (present in Mexiconnus );

- from Neladius in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Neladius ); the tempora shorter than eyes (much longer than eyes in Neladius ); the pronotum with lateral carinae and antebasal pits (absent in Neladius ); the basisternal part of prosternum much shorter than the coxal part (subequal in length in Neladius ); the mesoscutellum not exposed between elytral bases (in Ne- ladius exposed); the mesoventral intercoxal process present (absent in Neladius ); metacoxae laterally reaching lateral margins of metaventrite (broadly separated from sides of metaventrite in Neladius ); the aedeagus lacking parameres (present in Neladius );

- from Neuraphes in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Neuraphes ); the lateral sutures of submentum meeting posteriorly (broadly separated in Neuraphes ); the pronotum lacking transverse groove and median longitudinal wrinkle or carina (present in Neuraphes ); the aedeagus lacking parameres (present in Neuraphes );

- from Obesoconnus in the ant-like body form (compactly oval in Obesoconnus ); the head with a distinct occipital constriction, with small eyes (lacking constriction and with conspicuously large eyes in Obesoconnus ); the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Obesoconnus ); the lateral sutures of submentum meeting posteriorly (broadly separated in Obesoconnus ); the hypostomal ridges complete (incomplete in Obesoconnus ); the pronotum lacking transverse groove (present in Obesoconnus ); the prosternum strongly convex posteromedially (deeply emarginate posteromedially in Obeso- connus); the mesoscutellum not exposed between elytral bases (in Obesoconnus exposed); the aedeagus lacking parameres and the basal ‘pumping apparatus’ (both present in Obesoconnus );

- from Palaeoscydmaenus in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Palaeoscydmaenus ); the lateral sutures of submentum nearly meeting posteriorly (broadly separated in Palaeoscydmaenus ); the pronotum lacking transverse groove (present in Palaeoscydmaenus ) but with lateral carinae (absent in Palaeoscydmaenus ); the mesoventrite with a carinate mesoventral intercoxal process (absent in Palaeoscydmaenus ); the aedeagus lacking parameres (present in Palaeoscydmaenus );

- from Rutaraphes in the hypostomal ridges complete (obliterated in posterior half in Rutaraphes ); the pronotum lacking a median antebasal tubercle (present in Rutaraphes ); and the aedeagus lacking an elongate inner apodeme (with a conspicuous sclerotized apodeme in Rutaraphes );

- from Scydmaenilla in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Scydmaenilla ); the lateral sutures of submentum nearly meeting posteriorly (broadly separated in Scydmaenilla ); the pronotum lacking transverse groove (present in Scydmaenilla ), but with lateral carinae in the posterior third (absent in Scydmaenilla ); the metaventral intercoxal process with a pair of pointed lateral spines (with a pair of short lateral subtriangular, blunt projections in Scydmaenilla ); the aedeagus lacking parameres (present in Scydmaenilla );

- from Scydmoraphes in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Scydmoraphes ); the lateral sutures of submentum nearly meeting posteriorly (broadly separated in Scydmoraphes ); the pronotum lacking transverse groove (present in Scydmoraphes ); the hypomeral ridges absent (present in Scydmoraphes ); the mesoscutellum not exposed between elytral bases (in Scydmoraphes exposed); the aedeagus lacking parameres (present in Scydmoraphes );

- from Siamites in the head, ventral thorax and abdomen lacking rosettes of thick bristles, also sides of head and pronotum lacking bristles (all present in Siamites ); the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Siamite); the pronotum lacking a transverse groove (present in Siamites ); the hypomeral ridges absent (nearly complete in Siamites ); the aedeagus lacking parameres (present in Siamites );

- from Stenichnaphes the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Stenichnaphes ); the lateral sutures of submentum nearly meeting posteriorly (broadly separated in Stenichnaphes ); the pronotum lacking transverse groove (present in Stenichnaphes ); the mesoventrite with a carinate mesoventral intercoxal process (absent in Stenichnaphes ); the aedeagus lacking parameres (present in Stenichnaphes );

- from Stenichnodes in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Stenichnodes ); the lateral sutures of submentum nearly meeting posteriorly (broadly separated in Stenichnodes ); the pronotum lacking transverse groove (present in Stenichnodes ), but with lateral carinae (absent in Stenichnodes ); hypomeral ridges absent (present in Stenichnodes ); the aedeagus lacking the basal pumping apparatus (present in Stenichnodes );

- from Stenichnus in subtriangular, flat mandibles (narrow, falciform, nearly cylindrical in cross-section in Stenichnus ); the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Stenichnus ); the lateral sutures of submentum meeting posteriorly (broadly separated in Stenichnus ); the mesoscutellum not exposed between elytral bases (in Stenichnus exposed); the pronotum with lateral carinae in the posterior third (absent in Stenichnus ); the metaventral intercoxal process with a pair of long pointed lateral spines (with a pair of short lateral subtriangular, blunt projections in Stenichnus ); the aedeagus lacking parameres (present in Stenichnus );

- from Zeanichnus in the frons with deep supraantennal notches and impressed at middle (notches absent and frons not impressed in Zeanichnus ); the pronotum lacking a transverse groove (present in Zeanichnus ) but with lateral carinae in the posterior third (absent in Zeanichnus ); the aedeagus lacking parameres (present in Zean- ichnus).

Figures

FIGURES 8–9. Morphological structures of Parascydmus corpusculum. Dorsal habitus of male (8); head, prothorax and elytral base in dorsal view (9). Abbreviations: abp, antebasal pit; bef, basal elytral fovea; lc, lateral carina.

FIGURES 10–11. Morphological structures of Parascydmus corpusculum. Head, prothorax and anterior portion of pterothorax in ventral view (10); pterothorax and abdomen in ventral view (11). Abbreviations: ar, anterior ridge; bst, basisternal portion of prosternum; gp, gular plate; gs, gular suture; hr, hypostomal ridge; lss, lateral suture of labium; mn, mentum; msvp, mesoventral intercoxal process; mt, mesal tooth; mtvp, metaventral intercoxal process; pcr, procoxal rest; pre, prepectus; smn, submentum.

FIGURES 12–14. Aedeagus of Parascydmus corpusculum in ventral (12) and lateral (13) views and original set of labels of lectotype (14).