Neladius Casey, 1897

Jałoszyński, Paweł, 2017, Status of Nearctic subgenera of Microscydmus revisited (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4358 (3) : -

Genus Neladius Casey , stat. rest.

Neladius Casey, 1897: 498 . Type species: Neladius tenuis Casey, 1897 (monotypy). Synonymized with Microscydmus (Delius) by Franz (1985); removed from synonymy and placed as subgenus of Microscydmus by O'Keefe (1998).

Revised diagnosis. Head short, transverse, with occipital constriction broader than half HW; tempora and genae lacking bristles; eyes located much closer to mandibular bases than to posterior margin of head; submentum subtriangular, with lateral sutures extending posteromesally from mesal margins of cardines to posterior tentorial pits; hypostomal ridges complete, connected with posterior tentorial pits; antennae with distinct but slender trimerous club; prothorax lacking bristles; pronotum broadest in front of middle, without marked anterior corners, with distinct posterior corners, lacking lateral and sublateral carinae and antebasal pits or grooves; basisternal part of prosternum longer than coxal part; prosternal process or carina absent; notosternal sutures complete; hypomeral ridges complete and running parallel to notosternal sutures from anterior prosternal margin, demarcating very narrow adcoxal portion of hypomera; each elytron with one small and asetose basal fovea; wings, humeral calli and basal elytral impressions absent; mesoscutellum exposed in intact specimens; mesoventrite lacking intermesocoxal process, impressed between mesocoxae, unusually long in front of mesocoxal cavities and with a massive anterior ridge; mesoventrite anteriorly with a pair of shallow lateral impressions functioning as procoxal rests, impressions broadly separated at middle, with moderately sharp anterior and diffuse posterior margins, filled with setae; metaventral intercoxal process not separating metacoxae, short, subtriangular and deeply notched at middle; lateral corners of metacoxae separated from lateral metaventral margins by posterolateral lobes of metaventrite; aedeagus with symmetrical median lobe, asymmetrical endophallic structures and free parameres.

Redescription. Body small (BL ~ 1 mm), slender, moderately convex; constrictions between head and pronotum and between pronotum and elytra deep; body covered only with setae.

Head ( Figs 3 , 9, 12 ) slightly transverse, approximately pentagonal. Vertex and frons confluent; occipital constriction much broader than half HL; frons subtrapezoidal; frontoclypeal groove absent; antennal insertions moderately broadly separated; eyes located much closer to mandibular bases than to posterior margin of head. Mandibles subtriangular, robust, each with broad and blunt preapical tooth; mentum subhexagonal; labial palps short with elongate palpomeres II and III, narrowly separated; maxillary palps relatively short, palpomere III slightly more than twice as long as broad, palpomere III nearly half as long as III, with distal 2/3 slender; submentum subtriangular, with lateral sutures ( Fig. 12 ; lss); hypostomal ridges ( Fig. 12 ; hs) complete, extending from lateral margins of cardines posteromesally up to posterior tentorial pits. Posterior tentorial pits narrow, slotlike and located in transverse impression demarcating 'neck' region; gular plate broad, subtrapezoidal, with indistinct gular sutures. Antennae ( Fig. 3 ) moderately long, slender, with enlarged scape and pedicel and loosely assembled, distinctly delimited trimerous club.

Prothorax ( Figs 3 , 9, 12 ) with oval and weakly convex pronotum, its anterior margin confluent with rounded sides, so that anterior corners are not marked, posterior corners distinct, strongly obtuse-angled, posterior margin arcuate; pronotal base lacking pits, grooves and carinae. Basisternal part of prosternum ( Fig. 12 ; bst) slightly longer than coxal part; prosternum between procoxae with vestigial, weakly elevated and diffuse carina; notosternal sutures ( Fig. 12 ; nss) complete; hypomeral ridges ( Fig. 12 ; hyr) complete and running from anterior margin of prothorax parallel to notosternal sutures, demarcating remarkably narrow and long adcoxal portions of hypomera. Position of procoxae indicates closed procoxal cavities.

Mesoscutellum exposed in intact specimens, subtriangular with broadly rounded apex ( Fig. 9 ).

Mesoventrite conspicuously long, with shallow anterolateral impressions functioning as procoxal rests ( Fig. 14 ; pcr), which are broadly separated at middle and have moderately sharply defined anterior margins, while posteriorly become gradually shallower, impressions are densely filled with setae; area between mesocoxae lacking process or carina, distinctly impressed and partly setose.

Metaventrite broadened posteriorly; metaventral intercoxal process ( Fig. 15 ; mtvp) short, subtriangular, deeply and narrowly notched at middle, not separating metacoxae.

Metacoxae ( Fig. 15 ) separated from lateral metaventral margins by broad, rounded posterolateral lobes of ventrite.

Elytra ( Fig. 3 ) oval, elongate; each with one vestigial asetose basal fovea ( Fig. 8 ; bef) located close to mesoscutellum; basal impressions and humeral calli absent.

Hind wings absent.

Abdomen ( Fig. 15 ) shorter than metaventrite; suture between sternite VII and VIII barely discernible.

Legs ( Fig. 3 ) moderately long, with particularly short and robust tarsi.

Aedeagus ( Figs 18–19 ) with symmetrical, thin-walled median lobe, asymmetrical endophallic sclerites and free parameres.

Remarks. Neladius is another genus with the lateral sutures of submentum, and this character alone excludes it from Microscydmus , which does not have such sutures. Moreover, Microscydmus has a carinate mesoventral intercoxal process, which Neladius entirely lacks. Morphological differences in relation to the remaining genera with the submentum demarcated laterally by sutures are given below (only some characters are listed):

- Neladius differs from Alloraphes in: a trimerous antennal club (antennae gradually thickened in Alloraphes ); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Alloraphes ); labial palps much shorter than mentum (longer than mentum in Alloraphes ); exposed posterior tentorial pits (pits hidden in a narrow transverse groove demarcating the 'neck' region in Alloraphes ); the basisternal part of prosternum slightly longer than the coxal part (as long as 1/4–1/5 of the coxal part in Alloraphes ); the inner (adcoxal) part of hypomeron extremely narrow, forming a long strip, which is narrower than 1/5 of the lateral part of hypomeron (adcoxal part of hypomeron is as broad as 1/3 or more of the lateral part in Alloraphes ); the pronotal base lacking pits or grooves (two pits connected by a transverse groove in Alloraphes ); each elytron with one basal fovea (two foveae in Alloraphes ); mesoventral procoxal rests filled with setae and broadly separated at middle (asetose and narrowly separated in Alloraphes ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a carinate mesoventral intercoxal process in Alloraphes ); the anterior metaventral process absent (present in Alloraphes ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Alloraphes ); the aedeagus lacking defined diaphragm (basal diaphragm in Alloraphes );

- Neladius differs from Austrostenichnus in: a trimerous antennal club (antennae gradually thickened in Austrostenichnus ); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Austrostenichnus ); labial palps much shorter than mentum (longer than mentum in Austrostenichnus ); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Austrostenichnus ); the basisternal part of prosternum slightly longer than the coxal part (distinctly shorter than coxal part in Austrostenichnus ); hypomeral ridges present (absent in Austrostenichnus ); the pronotal base lacking pits or groove (two pits connected by a transverse groove in Austrostenichnus ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Austrostenichnus );

- Neladius differs from Leptoderoides in: a trimerous antennal club (antennae gradually thickened in Leptoderoides); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Leptoderoides); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Leptoderoides); the basisternal part of prosternum slightly longer than the coxal part (much shorter than coxal part in Leptoderoides); the pronotal base lacking a transverse impression (present in Leptoderoides); sublateral pronotal carinae absent (present in Leptoderoides); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a carinate mesoventral intercoxal process in Leptoderoides); mesoventral procoxal rests densely setose (asetose in Leptoderoides); the anterior metaventral process absent (present in Leptoderoides); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Leptoderoides);

- Neladius differs from Mexiconnus in: strongly elongate posterior tentorial pits (pits nearly circular in Mexiconnus ); long hypostomal ridges reaching posterior tentorial pits (not reaching tentorial pits in Mexiconnus ); the pronotal base lacking pits or grooves (transverse groove present in Mexiconnus ); mesoventral procoxal rests densely setose (asetose in Mexiconnus ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a carinate mesoventral intercoxal process in Mexiconnus ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Mexiconnus ); each elytron with one basal fovea (two vestigial foveae in Mexiconnus );

- Neladius differs from Delius in: tempora and sides of pronotum covered only with thin setae (with long, thick bristles in Delius ); the pronotum lacking any antebasal structures (with pits and a transverse groove in Delius ); hypomeral ridges running from the anterior margin of prothorax, demarcating extremely narrow inner parts of hypomera, which are longer than the prosternum (in Delius hypomeral ridges present only in the adcoxal region of each hypomeron, each demarcating an inner part of hypomeron, which is much shorter than half the length of prosternum); the area between mesocoxae lacking carina, distinctly concave (mesocoxae separated by a carinate mesoventral intercoxal process in Delius );

- Neladius differs from Neuraphes in: a trimerous antennal club (antennae gradually thickened in Neuraphes ); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Neuraphes ); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Neuraphes ); the basisternal part of prosternum slightly longer than the coxal part (distinctly shorter than coxal part in Neuraphes ); hypomeral ridges present (absent in Neuraphes ); the pronotum lacking lateral carinae (sides of pronotum developed as carinate edges in Neuraphes ); the pronotal base lacking pits or grooves (with a transverse impression disrupted at middle by a gap or a longitudinal wrinkle in Neuraphes ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a carinate mesoventral intercoxal process in Neuraphes ); each elytron with one very small and asetose basal fovea (one large fovea filled with setae in Neuraphes ); the anterior metaventral process absent (present in Neuraphes ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Neuraphes );

- Neladius differs from Obesoconnus in: a general body form, which is 'ant-like', i.e., with deep constrictions between the head and pronotum and between pronotum and elytra (very stout body with shallow constrictions in Obesoconnus ); a trimerous antennal club (antennae gradually thickened in Obesoconnus ); a transverse head with distinct tempora, occipital constriction and small eyes widely separated from antennal cavities (head round, lacking tempora and occipital constriction, with very large eyes adjacent to antennal cavities in Obesoconnus ); hypostomal ridges posteriorly reaching posterior tentorial pits (not reaching pits in Obesoconnus ); the maxillary palpomere IV much longer than broad at base, slender (palpomere IV very stout, about as long as broad in Obesoconnus ); the prosternum about as long as half of prothorax, with the basisternal part longer than the coxal part (prosternum remarkably short in Obesoconnus , only about as long as 1/4 of prothorax, with vestigial basisternal part); the inner (adcoxal) part of each hypomeron extremely narrow, forming a long strip, which is narrower than 1/5 of the lateral part of hypomeron (adcoxal part of hypomeron as broad as nearly 1/3 of the lateral part in Obesoconnus ); the pronotum longer than wide, lacking lateral edges or carinae (pronotum much broader than long, with distinct lateral carinae in the posterior third in Obesoconnus ); the pronotal base lacking pits or grooves (with a transverse groove connecting two lateral and one median pits in Obesoconnus ); mesoventral procoxal rests filled with setae (asetose in Obesoconnus ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Obesoconnus ); the aedeagus lacking a defined diaphragm (basal diaphragm present in Obesoconnus ); - Neladius differs from Palaeoscydmaenus in: a trimerous antennal club (antennae gradually thickened in Palaeoscydmaenus ); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Palaeoscydmaenus ); labial palps much shorter than mentum (longer than mentum in Palaeoscydmaenus ); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Palaeoscydmaenus ); hypomeral ridges present (absent in Palaeoscydmaenus ); the pronotal base lacking a transverse groove (with a groove in Palaeoscydmaenus ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Palaeoscydmaenus );

- Neladius differs from Rutaraphes in: a trimerous antennal club (antennae gradually thickened in Rutaraphes); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Rutaraphes); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Rutaraphes); lateral sutures of submentum posteriorly separated (connected in Rutaraphes); hypostomal ridges reaching posterior tentorial pits (not reaching pits in Rutaraphes); the basisternal part of prosternum slightly longer than the coxal part (distinctly shorter than coxal part in Rutaraphes); hypomeral ridges present (absent in Rutaraphes); the prosternal process indistinct, diffuse (carinate and sharply demarcated in Rutaraphes); the pronotum lacking lateral carinae (sides of pronotum in posterior half developed as carinate edges in Rutaraphes); the pronotal base lacking pits or grooves (with four pits and a posteromedian tubercle in Rutaraphes); mesoventral procoxal rests filled with setae (asetose in Rutaraphes); metacoxae not separated, spines of metaventral process shorter than 1/4 of metacoxal length (metacoxae distinctly separated by two very long spines reaching nearly the posterior margin of each metacoxa in Rutaraphes); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Rutaraphes); the aedeagus with parameres, lacking a defined diaphragm (aedeagus lacking parameres and with a ventral subapical diaphragm in Rutaraphes);

- Neladius differs from Scydmaenilla in: a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Scydmaenilla ); labial palps much shorter than mentum (longer than mentum in Scydmaenilla ); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Scydmaenilla ); the basisternal part of prosternum slightly longer than the coxal part (distinctly shorter than the coxal part in Scydmaenilla ); hypomeral ridges present (absent in Scydmaenilla ); the pronotal base lacking pits or grooves (two pits connected by a transverse groove in Scydmaenilla ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a subtriangular mesoventral intercoxal process in Scydmaenilla ); the anterior metaventral process absent (present in Scydmaenilla ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Scydmaenilla );

- Neladius differs from Scydmoraphes in: a trimerous antennal club (antennae gradually thickened in Scydmoraphes ); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Scydmoraphes ); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Scydmoraphes ); the basisternal part of prosternum slightly longer than the coxal part (distinctly shorter than coxal part in Scydmoraphes ); the inner (adcoxal) part of each hypomeron extremely narrow, forming a long strip, which is narrower than 1/5 of the lateral part of hypomeron (adcoxal part of hypomeron as broad as about 1/3 of the lateral part in Scydmoraphes ); the pronotum lacking lateral carinae (sides of pronotum developed as carinate edges in Scydmoraphes , at least in posterior third); the pronotal base lacking a transverse groove (with transverse impression or groove in Scydmoraphes ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a subtriangular mesoventral intercoxal process in Scydmoraphes ); the anterior metaventral process absent (present in Scydmoraphes ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Scydmoraphes );

- Neladius differs from Siamites in: lacking thick bristles (bristles in Siamites present on the head, prothorax, mesoventrite, metaventrite and abdominal sternites); lateral sutures of submentum posteriorly separated (connected in Siamites ); the basisternal part of prosternum slightly longer than the coxal part (distinctly shorter than coxal part in Siamites ); the basisternal part of prosternum slightly longer than the coxal part (distinctly shorter than coxal part in Siamites ); hypomeral ridges complete (ridges anteriorly obliterated in Siamites ); the pronotum broadest in front of middle (broadest at base or shortly in front of base in Siamites ); the pronotum lacking lateral carinae (sides of pronotum developed as carinate edges in Siamites , at least in the posterior third); the pronotal base lacking a transverse groove (with A transverse impression deepened at each end in Siamites ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a carinate mesoventral intercoxal process in Siamites ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Siamites );

- Neladius differs from Stenichnaphes in: a trimerous antennal club (antennae gradually thickened in Stenichnaphes ); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Stenichnaphes ); labial palps much shorter than mentum (longer than mentum in Stenichnaphes ); the basisternal part of prosternum slightly longer than the coxal part (only as long as 1/4 of the coxal part in Stenichnaphes ); hypomeral ridges present (absent in Stenichnaphes ); the pronotum lacking lateral carinae (lateral carinae, though blunt, present in the posterior half or third of pronotum in Stenichnaphes ); the pronotal base lacking pits or grooves (with a transverse groove connecting lateral impressions in Stenichnaphes ); each elytron with one small but distinct basal fovea (two vestigial, barely discernible foveae in Stenichnaphes ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Stenichnaphes );

- Neladius differs from Stenichnodes Franz, 1966 in: a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Stenichnodes ); labial palps much shorter than mentum (longer than mentum in Stenichnodes ); exposed posterior tentorial pits (pits hidden in a narrow transverse groove demarcating the 'neck' region in Stenichnodes ); the basisternal part of prosternum slightly longer than the coxal part (shorter than coxal part in Stenichnodes ); the inner (adcoxal) part of each hypomeron extremely narrow, forming a long strip in ventral view narrower than 1/5 of the lateral part of hypomeron (adcoxal part of hypomeron as broad as about 1/3 of the lateral part in Stenichnodes ); the pronotal base lacking pits or grooves (with a transverse groove connecting lateral pits in Stenichnodes ); mesoventral procoxal rests filled with setae (asetose in Stenichnodes ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a carinate mesoventral intercoxal process in Stenichnodes ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Stenichnodes ); the aedeagus with parameres, lacking a defined diaphragm (lacking parameres and with a basal diaphragm in Stenichnodes );

- Neladius differs from Stenichnus in: a trimerous antennal club (antennae gradually thickened in Stenichnus ); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Stenichnus ); mandibles subtriangular (falciform and very slender in Stenichnus ); labial palps much shorter than mentum (longer than mentum in Stenichnus ); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Stenichnus ); the basisternal part of prosternum slightly longer than the coxal part (distinctly shorter than coxal part in Stenichnus ); hypomeral ridges present (absent in Stenichnus ); the pronotal base lacking pits or grooves (with a various number of pits or a row of large punctures in Stenichnus ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a carinate mesoventral intercoxal process in Stenichnus ); the anterior metaventral process absent (present in Stenichnus ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Stenichnus );

- Neladius differs from Zeanichnus in: a trimerous antennal club (antennae with an indistinctly delimited tetramerous club or gradually thickened in Zeanichnus ); a transverse head with eyes located anteriorly (subtriangular, elongate head with eyes located posteriorly in Zeanichnus ); labial palps much shorter than mentum (longer than mentum in Zeanichnus ); exposed posterior tentorial pits (hidden in a narrow transverse groove demarcating the 'neck' region in Zeanichnus ); long hypostomal ridges reaching to posterior tentorial pits (not reaching tentorial pits in Zeanichnus ); hypomeral ridges present (absent in Zeanichnus ); the pronotal base lacking pits or grooves (two pits connected by a transverse groove in Zeanichnus ); the intermesocoxal region concave, lacking process or carina (mesocoxae separated by a subtriangular mesoventral intercoxal process in Zeanichnus ); the anterior metaventral process absent (present in Zeanichnus ); metacoxae laterally broadly separated from lateral metaventral margins by rounded posterolateral lobes of metaventrite projecting posteriorly (metacoxae laterally reaching lateral metaventral margins in Zeanichnus ).

Figures

FIGURES 1–6. Microscydmus (Opresus) misellus (LeConte) (1, 4); Delius robustulus Casey (2, 5); Neladius tenuis Casey (3, 6). Dorsalhabitus of lectotypes (1–3) and their historical sets of labels (4–6).

FIGURES 7–12. Microscydmus (Opresus) misellus (LeConte) (7, 10); Delius robustulus Casey (8, 11); Neladius tenuis Casey (9, 12). Head, pronotum and elytral bases in dorsal view (7–9); head, prothorax and anterior portion of pterothorax in ventral view (10–12). Abbreviations: abp, antebasal pit; bef, basal elytral fovea; bst, basisternal part of prosternum; hr, hypostomal ridge; hyr,hypomeral ridge; lss, lateral suture of submentum; nss, notosternal suture; pcr, procoxal rest.

FIGURES 13–15. Microscydmus (Opresus) misellus (LeConte) (13); Delius robustulus Casey (14); Neladius tenuis Casey (15); pterothorax and abdomen in ventral view. Abbreviations: msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; pcr, procoxal rest; pm, paramere; stVII–VIII, abdominal sternite VII–VIII.

FIGURES 16–19. Delius robustulus Casey (16–17); Neladius tenuis Casey (18–19). Aedeagus in ventral (16, 18) and lateral (17, 19) views.