Euconnus

Jałoszyński, Paweł, 2016, Taxonomy of ' Euconnus complex'. Part VIII. Subgenera Napoconnus, Himaloconnus and Nepaloconnus removed from Euconnus (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4103 (5), pp. 463-472 : 467-470

2. Morphological structures and taxonomic status of Euconnus ( Himaloconnus Franz )

The general body shape of Euconnus (Himaloconnus) shutjensis ( Fig. 2 ) is similar to that of many species of Euconnus , especially the subgenus Napochus .

The head capsule ( Figs 2 , 13 ) is divided into the posterior part ('neck' region) and anterior, exposed part by an occipital constriction broader than half width of head. The anterior part of the head is strongly elongate and slightly flattened; vertex distinctly demarcated from the 'neck' region and not bulging posterodorsally; frons subtrapezoidal; antennal insertions moderately broadly separated; compound eyes located anteriorly and the tempora are much longer than eyes. The tempora and genae are covered with thick bristles ( Figs 13, 14 ). The posterior tentorial pits ( Fig. 14 ; ptp) are small, circular and located slightly in front of the transverse impression demarcating ventrally the anterior and posterior parts of the head capsule; the gular plate ( Fig. 14 ; gp) is broad and subtrapezoidal, but with its anterior portion adjacent to the tentorial pits narrowed and elongate. The submentum ( Fig. 13 ; smn) is not demarcated laterally by sutures, bearing shallow and broad impression with presumably glandular openings ( Fig. 15 ), and hypostomal ridges ( Fig. 14 ; hr) are long and posteriorly extending up to the level of posterior tentorial pits, but the ends of ridges are located laterally to the pits. Most of these characters can be found in Euconnus , except for the hypostomal ridges running laterad the posterior tentorial pits (in Euconnus s. str., Napochus , Filonapochus , Tetramelus , Paratetramelus , Heteroconnus and Glabriconnus the posterior ends of both ridges are very close to posterior tentorial pits, typically in front of each pit; in Rhomboconnus the ridges are connected at middle in front of the pits); also the presumably glandular impression of the submentum is unique for Himaloconnus . A pair of enigmatic structures ( Fig. 14 ;?) can be seen at each side of the prementum; these are nearly circular flat lobes which can represent modified (i.e., enlarged and lacking microtrichia) lateral lobes of the hypopharynx. However, in the studied specimens the mandibles are tightly closed and any attempts to open them could easily result in damaging the mouthparts. Therefore, it was not possible to see where these lobes are inserted; additional material available for disarticulation is required to clarify the nature of these unusual structures, which are not known in any species of Scydmaeninae studied so far by the author.

The antennae ( Fig. 4 ) of Euconnus (Himaloconnus) shutjensis are moderately long, with scape and pedicel elongate and proximal flagellomeres subcylindrical and compactly assembled; the club is composed of three antennomeres subequal in width and loosely assembled. The antennae resemble those of Napochus , except for being three-, and not four-segmented.

The prothorax of Euconnus (Himaloconnus) shutjensis in dorsal view ( Figs 4 , 13 ) is short and subtrapezoidal, with sides strongly rounded and convergent anteriorly, the pronotum is broadest near base. The pronotal base bears one pair of small but distinct lateral antebasal pits ( Fig. 13 ; lab). The general shape of pronotum is similar to that of Napochus , except for the strongly rounded sides.

The prosternum ( Fig. 16 ) is short; the prosternal process ( Fig. 16 ; psp) rudimentary, carinate; the notosternal sutures ( Fig. 16 ; nss) seem complete (but they are only partly visible in the studied specimen); the hypomeral ridges ( Fig. 16 ; hyr) are obliterated anteriorly and posteriorly (i.e., not connected to notosternal sutures or anterior prothoracic margin anteriorly and not connected to the posterior hypomeral margin posteriorly); the sides of prothorax are covered with thick bristles. These are characters similar to those known in Napochus , except for incomplete hypomeral ridges.

The mesoventral structures of Euconnus (Himaloconnus) shutjensis differ from those of any hitherto reviewed subgenus of Euconnus in the mesoventral intercoxal process ( Fig. 17 ; msvp), which in a cross-section is T-shaped, i.e., its ventral surface is expanded laterally, much broader than in any Euconnus , the mesoventral process is broadened posteriorly and coarsely sculptured. The anterior portion of mesoventrite, where lateral impressions functioning as procoxal rests ( Fig. 17 ; pcr) are located, is unusually short.

The mesoventral cavities ( Figs 18–19 ) of Euconnus (Himaloconnus) shutjensis are unusual in having posterior 'curtains' composed of modified setae; similar fringes are located on mesocoxae; such structures are not known in other scydmaenines.

The metaventral intercoxal process of Euconnus (Himaloconnus) shutjensis ( Fig. 17 ; mtvp), is clearly different from structures found previously in Euconnus . The process is narrow and forming a pair of long spines touching at middle and projecting posteriorly, so that the metacoxae are narrowly separated. In Euconnus the metacoxae are distinctly separated and the metaventral process lacks the spines.

The elytra ( Figs 4 , 13 ) are oval, elongate, each with two distinct basal foveae, each with sparse setae inside. Foveae known in all previously studied subgenera of Euconnus , when well-developed, are asetose.

The aedeagus ( Figs 5–6 ) of Euconnus (Himaloconnus) shutjensis is symmetrical, with free and slender parameres, similar to copulatory organs in many genera of Glandulariini, including Euconnus ; it does not bear any unique characters that could be used to define Himaloconnus .

Conclusions. Morphological structures of Himaloconnus are similar to those of Euconnus , especially the subgenus Napochus , but the narrow metaventral intercoxal process with a pair of posteriorly directed spines excludes this taxon from Euconnus . The setose basal elytral foveae are not known in any Euconnus revised so far, the mouthparts with enigmatic lateral lobes and mesocoxal cavities with setal 'curtains' are unique for Himaloconnus , and the broad mesoventral intercoxal process is also not known in Euconnus . Consequently, Himaloconnus is here elevated to the generic rank.

Emended diagnosis of the genus Himaloconnus , status revised. Body approximately Napochus -like, i.e., the head with long tempora, pronotum subtrapezoidal, broadest near base and strongly narrowing anteriorly, and oval elytra, but the sides of pronotum strongly rounded; head and pronotum with thick bristles. Antenna with distinct club composed of antennomeres IX–XI; hypostomal ridges extending to the level of posterior tentorial pits, but their ends located laterally in relation to pits; mouthparts with rounded lateral lobes flanking prementum, which are presumably associated with hypopharynx; pronotum with one pair of small lateral pits, lacking sublateral carinae; hypomeral ridges incomplete, obliterated anteriorly and posteriorly; prosternum with rudimentary prosternal carina; mesoventral intercoxal process carinate, T-shaped in cross-section, broad and strongly elevated, broadening posteriorly, anteriorly not connected to anterior ridge of mesoventrite; metaventral intercoxal process narrowly separating metacoxae, with a pair of posteriorly directed, pointed spines adjacent at middle; each elytron with two distinct but small and setose basal foveae; aedeagus with free parameres.

Figures

FIGURES 1 – 9. Euconnus (Napoconnus) kubienai Franz (1 – 3); Euconnus (Himaloconnus) shutjensis Franz (4 – 6); and Euconnus (Nepaloconnus) khumbuensis Franz (7 – 9). Dorsal habitus of holotype male (1, 4, 7) and aedeagus in ventral (2, 5, 8) and lateral (3, 6, 9) views.

FIGURES 13 – 16. Morphological structures of Euconnus (Himaloconnus) shutjensis Franz. Head, prothorax and elytral base in dorsal view (13); head in ventral view (14); impression of submentum (15); prothorax and anterior portion of pterothorax in ventral view (16). Abbreviations: bef, basal elytral fovea; bst, basisternal part of prosternum; fr, frons; gp, gular plate; gs, gular suture; hr, hypostomal ridge; hyr, hypomeral ridge; lab, lateral antebasal pit; mn, mentum; mxp, maxillary palp; nss, notosternal suture; occ, occipital constriction; psp, prosternal process; ptp, posterior tentorial pit; smn, submentum; vt, vertex;?, unknown structure of mouthparts.

FIGURES 17 – 19. Morphological structures of Euconnus (Himaloconnus) shutjensis Franz. Pterothorax and abdomen in ventral view (17); right (18) and left (19) mesocoxal cavity in ventral view. Abbreviations: msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; pcr, procoxal rest; st 3 – 8, abdominal sternites 3 – 8; v 3, metaventrite.