Euconnus (Androconnus)

Jałoszyński, Paweł, 2018, Taxonomy of ' Euconnus complex'. Part XVII. Status of subgenera defined by male antennal characters: Androconnus Franz and Cladoconnus Reitter (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4415 (2), pp. 369-380 : 370-373

1. Morphological structures of Euconnus (Androconnus)

The general body shape of Euconnus bechyneae ( Fig. 1 ) does not deviate from that in many other species of Euconnus ; it is slender, moderately convex, with deep constrictions between the head and pronotum and between the pronotum and elytra.

The head capsule ( Figs 4 ̄5) is divided into the posterior 'neck' region and anterior, exposed part by an occipital constriction subequal to half width of the head. The anterior part of the head is slightly elongate; the vertex demarcated from the 'neck' region by a transverse impression and very weakly bulging posterodorsad; the frons subtrapezoidal, transverse; antennal insertions moderately broadly separated; composite eyes located anterolaterally; tempora much longer than eyes, rounded and distinctly convergent caudad. The tempora and genae/ postgenae are sparsely covered with long, thick bristles; additionally, there are two groups of 2¯3 modified, flattened and distally broadened setae on the postgenae.

Mouthparts ( Figs 4 ̄5) similar to those in most species of Euconnus ; mandibles subtriangular, evenly curved, lacking mesal teeth; mentum ( Fig. 5 ; mn) subhexagonal with narrowly separated and unremarkable labial palps and a small elongate ligula bearing a pair of short setae between the palps; submentum ( Fig. 5 ; smn) short and transverse; hypostomal ridges ( Fig. 5 ; hr) long and recurved, but posteriorly not reaching posterior tentorial pits ( Fig. 5 ; ptp), which are located in front of a transverse impression demarcating the 'neck' region ventrally, the pits are elongate, slot-like. Maxillae and maxillary palpomeres typical as in Euconnus s. str.; labrum transverse.

The antennae ( Figs 1 , 6 ¯8) are slender and strikingly long in relation to the body; in both sexes antennomeres VIĪXI form an indistinctly delimited, pentamerous club, which in males is broader than in females, and has three terminal antennomeres modified. In the type species of Androconnus , antennomeres IX and X have their mesal portions flattened or impressed, and the anteromesal margin of each forms a subtriangular projection. In the antennomere X ( Fig. 8 ), there is a glandular opening at base of the projection. The antennomere XI is asymmetrically impressed dorsally and dorsomesally. Apical portions of antennomeres VIĪX are covered with irregular granulation, and impressed portions of antennomere XI have scale-like microsculpture and are nearly asetose.

The prothorax ( Figs 4 ̄5) of Androconnus is bell-shaped, slightly elongate, broadest slightly behind middle, with rounded sides and more narrowing anteriorly than posteriorly, so that the anterior pronotal margin is shorter than posterior margin; anterior and posterior corners well-defined but obtuse-angled and blunt. The pronotal base bears two pairs of very small and shallow antebasal pits ( Fig. 4 ; abp), narrow but distinct transverse antebasal groove ( Fig. 4 ; abg), and short sublateral carinae ( Fig. 4 ; slc). In addition to thin setae, pronotum bears thick and sparse bristles on each side.

Ventral prothoracic structures are typical of Euconnus : the basisternal part of prosternum ( Fig. 5 ; bst) is much shorter than the coxal part; the intercoxal region lacks process or carina; notosternal sutures ( Fig. 5 ; nss) are complete; hypomeral ridges ( Fig. 5 ; hyr) complete and the inner (adcoxal) part of each hypomeron is distinctly microsculptured and asetose.

The mesoventrite ( Fig. 9 ) has a broad and well-defined anterior ridge, distinct anterior impressions functioning as procoxal rests ( Fig. 9 ; pcr), which are sharply demarcated anteriorly and separated at middle, but not demarcated posteriorly, and filled with sparse, short setae. The mesoventral intercoxal process ( Fig. 9 ; msvp) is keel-like, anteriorly connected to the anterior ridge and posteriorly fused with the metaventrite.

The mesoscutellum is not exposed in intact specimens ( Fig. 4 ).

The metaventrite ( Fig. 9 ) is slightly transverse; the metaventral intercoxal process ( Fig. 9 ; mtvp) is relatively narrow but distinctly separating metacoxae, its posterior margin is concave, and posterolateral corners rounded.

Each elytron bears two asetose, small and shallow but distinct basal elytral foveae ( Fig. 4 ; bef).

The aedeagus in the type species of Androconnus ( Figs 10 ̄12) is elongate, moderately strongly sclerotized, with free parameres bearing apical and subapical setae and two pairs of apical (dorsal and ventral) projections. Aedeagi illustrated by Franz (1986a) for other species of Androconnus are variable in form, some have similarly paired distal projections as those in E. bechyneae , and some have subtriangular, undivided apices; endophalli can be symmetrical or asymmetrical.

Conclusions. Androconnus has all the diagnostic characters of Euconnus (see Jałoszyński (2012), and can be maintained as a subgenus. Although it is similar to several other subgenera of Euconnus (see remarks below), it differs in a combination of several characters from each of them.

Remark. Androconnus differs from hitherto redefined subgenera of Euconnus in the following characters:

• from Austroconophron Franz, 1971 in pentamerous antennae (gradually thickened in Austroconophron ); pronotum with antebasal pits, groove and sublateral carinae (lacking any of those structures in Austroconophron ); • from Euconophron Reitter, 1909 in pentamerous antennal club (indistinctly tetramerous in Euconophron ); short mandibles lacking mesal teeth (strikingly long and slender mandibles, each with one mesal tooth in Euconophron ); hypostomal ridges not connected posteriorly (connected or nearly connected in Euconophron ); pronotum with an even number of antebasal pits (with an uneven number of pits in Euconophron , which has a median pit); anterolateral corners of prosternum weakly projecting anteriorly (strongly projecting, forming large subtriangular lobes in Euconophron );

• from Euconnus s. str. in pentamerous antennae (gradually thickened or indistinctly tetramerous in Euconnus s. str.); hypostomal ridges not connected posteriorly (connected or nearly connected in Euconnus s. str.); mandibles lacking mesal teeth (with one mesal tooth in Euconnus s. str.); antennae in males with modified antennomeres VIII–XI;

• from Filonapochus Franz, 1986b in pentamerous antennal club (antennae very slender and gradually thickened in Filonapochus ); elongate head (head short, round in Filonapochus ); head lacking ventrolateral cavities near occipital constriction; pronotum broadest only slightly behind middle (at base in Filonapochus ) and bearing antebasal pits, transverse groove and sublateral carinae (lacking any of those structures in Filonapochus ); • from Glabriconnus Jałoszyński, 2016b in an elongate head (in Glabriconnus head short, subpentagonal, ' Sciacharis -like'); pentamerous antennal club (antennae gradually thickened in Glabriconnus); mandibles lacking mesal teeth (one mesal tooth in Glabriconnus); pronotum broadest behind middle (in front of middle in Glabriconnus); sides of pronotum lacking longitudinal hypomeral grooves (present in Glabriconnus); pronotal base with two pairs of pits, transverse groove and sublateral carinae (only with one pair of pits in Glabriconnus); • from Heteroconnus Franz, 1963 in hypostomal ridges not reaching posterior tentorial pits; antennae with club (gradually thickened in Heteroconnus ); pronotum with rounded sides (constricted behind middle in Heteroconnus ); an unmodified pronotum in males (with a median impression, carinae and tufts of setae in Heteroconnus ); • from Napochus Thomson, 1859 in pentamerous (tetramerous in Napochus ) antennal club; pronotum broadest only slightly behind middle and strongly rounded at sides (subconical in Napochus ); prosternum lacking any trace of prosternal process (typically an indistinct carina present in Napochus , sometimes reduced);

• from Nodoconnus Franz, 1986b in elongate head (subpentagonal, ' Sciacharis -like' in Nodoconnus ); hypostomal ridges extending posteromesad and not connected at middle (ridges connected and forming one transverse carina parallel to the posterior mental margin in Nodoconnus ); pronotum broadest behind middle and rounded at sides (broadest in front of middle and with sinuate sides in Nodoconnus ); pronotal base with a transverse groove and sublateral carinae (only with one pair of diffuse pits in Nodoconnus );

• from Paratetramelus Franz, 1963 in elongate head ( Sciacharis -like, subpentagonal and short in Paratetramelus ); antennae with club (gradually thickened in Paratetramelus ); hypostomal ridges not connected posteriorly (connected in Paratetramelus );

• from Psomophus Casey, 1897 in pentamerous antennal club (trimerous in Psomophus );

• from Pycnophus Casey, 1897 in pentamerous antennal club (tetramerous in Pycnophus ); elongate head (large, subcircular, often broader than long in Pycnophus ); pronotum broadest slightly behind middle (typically at base in Pycnophus ) and bearing two pairs of pits and a transverse groove (one pair of pits and typically lacking groove in Pycnophus );

• from Rhomboconnus Franz, 1986a in ventral surface of head lacking a well-defined longitudinal groove connecting posterior tentorial pits and apices of hypostomal ridges; hypostomal ridges not connected posteriorly; tempora gradually, and not stepwise narrowing caudad and lacking a well-defined row of short and very dense bristles; pronotum with distinct sublateral carinae and transverse groove;

• from Tetramelus Motschulsky, 1870 in a short clypeus (strikingly long in Tetramelus ); mandibles lacking mesal teeth (one mesal tooth typically present in Tetramelus ); pronotum with sides rounded in posterior half (typically constricted near posterior third in Tetramelus ); pronotal base lacking median carina (present in Tetramelus ).

From each of these subgenera, except one, Androconnus differs not only in the modified antennae of males, but also in some other characters. The only exception seems to be Psomophus , and in future Androconnus and Psomophus may be placed as synonyms. However, the worldwide subgenus Psomophus requires further study to understand its limits and character variability, whereas Androconnus seems to represent a group of species welldefined not only morphologically, but also geographically (restricted to the northern part of Neotropical region) and may constitute a monophyletic unit. For this reason, I prefer to maintain Androconnus as a separate subgenus, pending further study. Androconnus and Psomophus are most similar to Euconnus s. str. and Austroconophron ; these taxa require a more comprehensive study.

Emended diagnosis of Euconnus (Androconnus) . Euconnus with strikingly long antennae; antennal club indistinctly pentamerous; antennomeres IX–XI modified in males, asymmetrical, with impressions and/or mesal tooth-like projections; head elongate, with vertex indistinctly bulging posterodorsad; tempora longer than eyes and covered with bristles; hypostomal ridges long but not reaching posterior tentorial pits and not connected posteriorly; mandibles short and lacking mesal teeth; pronotum broadest slightly behind middle, with rounded sides; pronotal base with paired pits, sublateral carinae and transverse groove; interprocoxal area lacking any trace of carina or process; sides of pronotum with bristles; basal elytral foveae small but distinct; metaventral intercoxal process distinctly emarginate.

Figures

FIGURES 1–3. Dorsal habitus. Euconnus (Androconnus) bechyneae Franz, male (1); Euconnus (Cladoconnus) motschulskyi (Sturm), male (2); Euconnus (Cladoconnus) denticornis (Müller & Kunze), female (3).

FIGURES 4–5. Morphological structures of Euconnus (Androconnus) bechyneae Franz, male. Head, prothorax and elytral base in dorsal view (4); head, prothorax and anterior portion of pterothorax in ventral view (5). Abbreviations: abg, antebasal groove; abp, antebasal pit; bef, basal elytral fovea; bst, basisternal part of prosternum; fr, frons; gp, gular plate; hr, hypostomal ridge; hyr, hypomeral ridge; mn, mentum; nss, notosternal suture; ptp, posterior tentorial pit; slc, sublateral carina; smn, submentum; vt, vertex.

FIGURES6–8. Morphological structures of Euconnus (Androconnus) bechyneae Franz, male.Distal portion of left antenna in dorsal (6) and mesal (7) views; antennomeres X–XI in mesal view (8). Abbreviations:anIX–XI,antennomere IX–XI.

FIGURES 9–12. Morphological structures of Euconnus (Androconnus) bechyneae Franz, male. Pterothorax and anterior portion ofabdomen inventral view (9); aedeagusinlateroventral (10), ventral (11) and lateral(12)views.Abbreviations:msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; pcr, procoxal rest.