Microscydmus, Saulcy & CroIssandeau and Penicillidmus, 1893

Jałoszyński, Paweł & Newton, Alfred F., 2017, Taxonomy of ' Euconnus complex'. Part XV. Disentangling the Euconnus - Sciacharis knot (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4344 (3), pp. 401-443 : 413-417

Microscydmus ( Valdivioconnus Franz , status rev.)

( Figs 8 , 26–29 , 40–41, 46)

Valdivioconnus Franz, 1980b: 252 (as subgenus of Euconnus ). Type specIes: Euconnus stenichniformis Franz, 1967a (des. orIg.). Transferred from Euconnus to subgenus of Sciacharis by Franz (1993a); subsequently mIsspelled Validioconnus ( Franz 1997: 165); here transferred to subgenus of Microscydmus Saulcy & Croissandeau.

Revised diagnosis. Microscydmus with the following combination of characters: head lacking bristles; submentum much longer than half length of mentum; sides of pronotum with conspicuous bristles; each elytron with two small asetose basal foveae; procoxal rests on mesoventrite filled with setae, their posterior margin marked by fine carina, area behind the carina not impressed.

Redescription. General body shape ( Fig. 8 ) elongate and moderately convex, pronotum flattened, body deeply constricted between head and pronotum and between pronotum and elytra.

Head ( Figs 26–27 ) small in relation to pronotum; divided by occipital constriction into large anterior and small posterior part ('neck' region), posterior part retracted into pronotum. Occipital constriction slightly broader than half width of head. Anterior part of head capsule convex dorsally and flattened ventrally, subtrapezoidal; tempora slightly longer than compound eyes; vertex transverse and not bulging posterodorsally, posteriorly demarcated by stepwise rounded ridge, anteriorly vertex confluent with subtrapezoidal frons; supraantennal tubercles distinct but weakly elevated; frontoclypeal groove absent. Gular plate ( Fig. 27 ; gp) broad and with indistinct gular sutures; posterior tentorial pits ( Fig. 27 ; ptp) nearly circular and located slightly in front of deep and well-defined transverse impression separating 'neck' region from anterior part of head. Tempora, genae and postgenae lacking bristles. Submentum ( Fig. 27 ; smn) subtrapezoidal, relatively long, much longer than half length of mentum; hypostomal ridges ( Fig. 27 ; hr) incomplete, marked only just behind cardines, not reaching middle between each cardo and posterior tentorial pit; mentum ( Fig. 27 ; mn) subtrapezoidal; prementum small and transverse, largely membranous; labial palps short; maxillae unmodified; mandibles only partly visible in the studied specimen, subtriangular and evenly curved, mesal margins not visible.

Antennae ( Fig. 8 ) long and slender, antennomeres IX–XI forming only slightly broadened club.

Prothorax ( Figs 26, 28 ) flattened, round, broadest in front of middle, with sides strongly rounded in anterior half and weakly rounded behind the widest site; anterior corners indistinct, posterior corners well-marked, obtuseangled; base with sublateral carinae ( Fig. 26 ; slc) and two pairs of antebasal pits ( Fig. 26 ; abp), of which inner pair connected by transverse groove. Prosternum ( Fig. 28 ) with basisternal part ( Fig. 28 ; bst) distinctly shorter than coxal part; notosternal sutures ( Fig. 28 ; nss) incomplete, marked at the anterior margin of prothorax but internalized at middle, again visible posteriorly, in anterolateral margin of each procoxal cavity, as arcuate suture curved anterolaterally; hypomeral ridges ( Fig. 28 ; hyr) complete, sinuate; procoxal cavities broadly closed; interprocoxal region with narrow, weakly elevated and diffuse carina; hypomera covered with bristles.

Mesothorax. Mesoscutellum in intact specimens entirely covered by posterior pronotal margin, its posterior tip not exceeding posterior margin of elytral articulating lobe. Mesoventrite ( Fig. 29 ) with a pair of transverse setose impressions functioning as procoxal rests ( Fig. 29 ; pcr) in anterior region, impressions separated at middle and posteriorly demarcated by fine carina, area behind carina not impressed; mesoventral intercoxal process ( Fig. 29 ; msvp) carinate, posteriorly fused with metaventrite.

Metathorax. Metaventrite ( Fig. 29 ) much longer than mesoventrite, subtrapezoidal; intermetacoxal area forming metaventral intercoxal process ( Fig. 29 ; mtvp) composed of two long spinces separated by narrow notch.

Elytra ( Figs 8 , 26 ) oval, with rounded apices and base nearly as wide as posterior pronotal margin; humeral calli and basal impressions distinct; each elytron with two very small asetose basal foveae ( Fig. 26 ; bef).

Metathoracic wings present.

Legs ( Fig. 8 ) moderately long and slender, unmodified (including protibial apices in male).

Abdomen elongate, gradually narrowing posteriorly, suture between two terminal visible sternites (i.e., VII and VIII) less distinct than between remaining sternites.

Aedeagus (Figs 40–41) stout, with symmetrical and weakly sclerotized median lobe; endophallic structures with asymmetrical distal sclerites, parameres slender, with apical setae.

Remarks. The type species of Valdivioconnus has numerous characters that do not occur in the type species of Sciacharis : trimerous antennal club; head with strongly shortened area behind the mentum, with circular posterior tentorial pits and deep, narrow groove demarcating ventrally the 'neck' region from anterior part of head capsule; hypostomal ridges obliterated shortly behind cardines; short and round pronotum with the inner pair of antebasal pits connected by transverse groove; the posterior portion of notosternal suture extending from prosternal cavity anteriorly and distinctly curved laterally to disappear near middle between cavity and hypomeral ridge; and the metaventral intermetacoxal process composed of two elongate spines separated at middle by a narrow notch. These characters do not occur also in Euconnus , but are diagnostic for Microscydmus Saulcy & Croissandeau, 1893 . Euconnus stenichniformis is also very small (body length 1.03 mm), as are all species of Microscydmus .

FIGURES 30–41. Aedeagus In ventral (30, 32, 34, 36, 38, 40) and lateral (31, 33, 35, 37, 39, 41) vIews. Euconnus (Austroconophron) tindoui Franz , comb. rest. (type specIes of Austroconophron), lectotype (30–31); Sciacharis (s. str.) lanosa (Broun) (type specIes of Allomaoria), lectotype (32–33); Magellanoconnus (s. str.) laurisilvae (Franz) , comb. rest. (type specIes of Magellanoconnus ), holotype (34–35); Neuraphoconnus caledonicus Franz , comb. rest. (type specIes of Neuraphoconnus ), lectotype (36–37) and paralectotype (38–39); Microscydmus (Valdivioconnus) stenichniformis (Franz) , comb. n. (type specIes of Valdivioconnus ), holotype (40–41).

Microscydmus is currently divided into six subgenera: Delius Casey, 1897 ( USA), Microscydmus s. str. (worldwide?), Neladius Casey, 1897 ( USA), Neoscydmus Franz, 1980b (Neotropical) , Parastenichnus Franz, 1970 (Oriental) , and Scydmomicrus Jałoszyński, 2014d ( Australia) . This subgeneric system requires revision due to unclear status of all of its Nearctic components (of which some will be removed from Microscydmus ; Jałoszyński in preparation) and the Neotropical Neoscydmus . Valdivioconnus , transferred here to subgenus of Microscydmus , differs from Microscydmus s. str. in the head lacking bristles (in Microscydmus s. str. bristles are distributed on tempora, genae and postgenae); submentum trapezoidal, much longer than half length of mentum ((in Microscydmus s. str. submentum strongly transverse, only about 1/3 as long as mentum); the posterior margins of procoxal rests on mesoventrite marked by fine carina, area behind the carina not impressed (in Microscydmus s. str. posterior margins of procoxal rests marked by a rapid, stepwise, deep transverse impression nearly as long as procoxal rests); and two very small asetose basal elytral foveae (in Microscydmus s. str. one large fovea filled with setae). Neladius and Delius do not belong in Microscydmus and their status will be clarified in a separate paper (Jałoszyński in preparation). Valdivioconnus differs from Scydmomicrus in two basal elytral foveae (in Scydmomicrus one asetose fovea); and the procoxal rests on mesoventrite densely setose (in Scydmomicrus completely asetose); additionally the sides of pronotum in the type species of Valdivioconnus are covered with conspicuous bristles (like in Microscydmus s. str.), whereas in Scydmomicrus either there are no bristles on the pronotum or a few scattered mostly on the ventral portions of hypomera and barely discernible in dorsal view. Valdivioconnus differs from Parastenichnus in two (vs. one) basal elytral foveae and the metaventrite lacking carinae (in Parastenichnus a distinct carina extends posteromesally from each mesocoxal projection and reaches about middle of metaventrite). Neoscydmus was described as having the mesoscutellum visible between elytral bases in intact specimens; apart from an unclear taxonomic status of this taxon, which may not belong in Microscydmus , this character alone is sufficient to distinguish it from Valdivioconnus , whose type species has the mesoscutellum not exposed.

Composition and distribution. Microscydmus (Valdivioconnus) currently includes 38 valid species names; this subgenus is distributed in Argentina, Chile and Peru.

Figures

FIGURES 1 – 9. RepresentatIves of all genus-group names prevIously or currently Included In Sciacharis; dorsal habItus. Euconnus (Austroconophron) tindoui Franz, comb. rest. (type specIes of Austroconophron) (1); Sciacharis (s. str.) lanosa (Broun) (type specIes of Allomaoria) (2); Sciacharis (s. str.) fulva Broun (type specIes of Sciacharis) (3); Sciacharis (Maorinus) alacer (Broun) (type specIes of Maorinus) (4); Magellanoconnus (s. str.) laurisilvae (Franz), comb. rest. (type specIes of Magellanoconnus) (5); Magellanoconnus (Anthicimimus) anthiciformis (Franz), comb. n. (type specIes of Anthicimimus) (6); Neuraphoconnus caledonicus Franz, comb. rest. (type specIes of Neuraphoconnus) (7); Microscydmus (Valdivioconnus) stenichniformis (Franz), comb. n. (type specIes of Valdivioconnus) (8); and Kangarooconnus carinifrons (Franz), comb. n. (type specIes of Kangarooconnus) (9).

FIGURES 26 – 29. MorphologIcal structures of Microscydmus (Valdivioconnus) stenichniformis (Franz), comb. n. (type specIes of Valdivioconnus). Head, prothorax and elytral base In dorsal vIew (26); head In ventral vIew (27); prothorax In ventral vIew (28); pterothorax In ventral vIew (29). AbbrevIatIons: abp, antebasal pIt; bef, basal elytral fovea; bst, basIsternal part of prosternum; gp, gular plate; hr, hypostomal rIdge; hyr, hypomeral rIdge; mn, mentum; msvp, mesoventral Intercoxal process; mtvp, metaventral Intermetacoxal process; nss, notosternal suture; pcr, procoxal rest; psp, prosternal process; ptp, posterIor tentorIal pIt; slc, sublateral carIna; smn, submentum.