Goniusa Casey, 1906

Gusarov, Vladimir I., 2003, A revision of the genus Goniusa Casey, 1906 (Coleoptera: Staphylinidae: Aleocharinae), Zootaxa 164, pp. 1-20 : 2-8

Goniusa Casey, 1906 ( Figs. 1­56)

Goniusa Casey, 1906: 348 (in tribe Bolitocharini Thomson, 1859).

Goniusa: Casey 1911: 208 (in tribe Bolitocharini ).

Goniusa: Fenyes, 1918: 19 (in subtribe Athetina Casey, 1910 of tribe Myrmedoniini Thomson, 1867).

Goniusa: Fenyes, 1920: 235 .

Goniusa: Bernhauer & Scheerpeltz, 1926: 597 (in subtribe Athetina ).

Goniusa: Blackwelder, 1952: 174 .

Goniusa: Kistner, 1976: 84 (in tribe Zyrini Bradley, 1930).

Goniusa: Seevers, 1978: 133 (in Goniusa group of tribe Athetini). Goniusa: Ashe in Newton, Thayer, Ashe & Chandler, 2000: 371 (in tribe Athetini, not assigned to subtribe).

Diagnosis. Goniusa can be distinguished from the other athetine genera by the combination of the following characters: body broad; antennal articles 5­10 slightly elongate ( Fig. 14) or slightly transverse; in dry specimens gaps between antennal articles inconspicuous; ligula split apically ( Fig. 6); labial palpus with setae,, and present; pronotum strongly transverse, 1.5­1.6 times as wide as long, with microsetae directed posteriorly along the midline; in lateral portions of the disc microsetae directed posteriorly and obliquely laterally (Type V, Benick & Lohse 1974) ( Fig. 12); pronotal macrosetae short; pronotal hypomera fully visible in lateral view; medial macroseta of mesotibia inconspicuous, shorter than tibial width; tarsal formula 4­5 ­ 5; metatarsal segment 1 slightly shorter than segment 2; one empodial seta; abdominal sterna with numerous semierect macrosetae, sternum 8 with 30­60 macrosetae ( Figs. 21, 24); male pronotum with broad medial impression that is half as wide as pronotum, deeper in the posterior half, postero­lateral portions of the impression with less dense microsculpture, without punctation and pubescence; male sternum 8 with broad apical emargination, apical portion of the sternum membranous ( Fig. 21); aedeagus with narrow but blunt apex ( Figs. 25, 48); medial lamellae of internal sac absent ( Figs. 30, 56); copulatory piece trough­shaped, with pointed apex ( Figs. 30­34); proximal portion of spermatheca with 2­3 coils ( Figs. 35­36).

Goniusa differs from Notothecta Thomson, 1858 in having abdominal sternum 8 with numerous (30­60) macrosetae ( Figs. 21, 24), male pronotum with broad medial impression, male sternum 8 with broad apical emargination, and different shape of the aedeagus and spermatheca.

Goniusa can be distinguished from similar­looking genera of the tribe Lomechusini by having longer and narrower mesothoracic process ( Figs. 13; 17­18); by shorter galea with its apical lobe only slightly projecting beyond the apex of lacinia ( Figs. 8; 16, 19) and stronger setae on its internal margin ( Figs. 11; 16).

Description. Length 3.2­4.2 mm, pronotal width 0.84­1.07 mm. Body broad, reddish brown to dark brown with darker head and brownish red appendages.

Head transverse; eyes large, temple length to eye length ratio 0.6 ­1.0; infraorbital carina very weak, complete, incomplete or absent altogether. Antennal article 2 as long as article 3, article 4 elongate, 5­10 slightly elongate or slightly transverse, apical article without coeloconic sensilla, longer than articles 9 and 10 combined ( Fig. 14). In dry specimens gaps between antennal articles inconspicuous. Labrum ( Fig. 1) transverse, with straight anterior margin. Adoral surface of labrum (epipharynx) as in Fig. 2. Mandibles ( Figs. 3­5) broad, right mandible with small medial tooth; dorsal molar area with velvety patch consisting of very small denticles (poorly visible at 400 x). Maxilla ( Figs. 8­11) with galea projecting slightly beyond apex of lacinia; apical lobe of galea covered with numerous fine and short setae; internal margin of galea with long subapical setae ( Fig. 11); apical 1 / 7 of lacinia with row of closely spaced spines, middle portion produced medially and covered with numerous setae ( Figs. 9­10). Labium as in Figs. 6 ­7, 15; ligula split apically; medial area of prementum without pores but with 5 pseudopores, lateral areas with 2 pores, single setose pore and 12­16 pseudopores ( Fig. 6). Hypopharyngeal lobes as in Fig. 7. Labial palpus with setae,, and present. Mentum ( Fig. 15) with concave anterior margin.

Pronotum ( Figs. 12, 37­ 41) strongly transverse, with microsetae directed posteriorly in midline; in lateral portions of disc microsetae directed posteriorly and obliquely laterally (Type V, Benick & Lohse 1974); macrosetae short; hypomera fully visible in lateral view. Meso­ and metasternum as in Fig. 13, mesosternal process narrow, extending about ½ length of mesocoxal cavities, metasternal process short, mesosternum and mesosternal process not carinate medially; relative lengths of mesosternal process: isthmus: metasternal process in ratio of about 2: 1: 1; mesocoxal cavities margined posteriorly; mesocoxae narrowly separated. Medial macroseta of mesotibia inconspicuous, shorter than tibial width. Tarsal segmentation 4­5 ­ 5, metatarsal segment 1 slightly shorter than segment 2. One empodial seta, half as long as claws. Posterior margin of elytra slightly concave near postero­lateral angle. Wings fully developed.

Abdominal terga 3­5 with moderate basal impressions. Tergum 7 1.1­1.2 times as long as tergum 6. Punctation on terga 6­7 sparser than on terga 3­5. Tergum 7 with wide white palisade fringe. Abdominal sterna with numerous semierect macrosetae, sternum 8 with 30­60 macrosetae.

Male pronotum with broad medial impression that is half as wide as pronotum, deeper in posterior half, postero­lateral portions of the impression with less dense microsculpture, without punctation and pubescence. Compared to female, male pronotum matte, with stronger microsculpture and weaker punctation. Male sternum 8 with broad apical emargination, apical portion of the sternum membranous ( Fig. 21); aedeagus with narrow but blunt apex ( Figs. 25, 48); medial lamellae of internal sac absent ( Figs. 30, 56); copulatory piece trough­shaped, with pointed apex ( Figs. 30­34); proximal portion of spermatheca with 2­3 coils ( Figs. 35­36).

Type species. Goniusa caseyi Gusarov , sp. n., by subsequent designation (see Discussion below), fixed under provisions of Article 70.3.

Discussion. When proposing the new generic name Goniusa, Casey (1906) included in a single species, Euryusa obtusa LeConte, 1866 , and this species would be the type of the genus by monotypy. However, my examination of the holotype of Euryusa obtusa ( MCZ) and the specimens labeled as “ Goniusa obtusa ” in the Casey collection, as well as my analysis of characters mentioned by Casey (1906) demonstrated that Casey’s concept of the species does not agree with that of LeConte (1866). In fact the holotype of Euryusa obtusa belongs to the genus known as Lypoglossa Fenyes, 1918 while Casey's specimens agree with current usage of the name " Goniusa obtusa ". The status of E. obtusa LeConte (nec Casey) will be discussed in a separate paper on the genus Lypoglossa . Since the type species of the genus Goniusa Casey, 1906 was misidentified by Casey (1906) the provisions of the Article 70.3 apply to it and the type species needs to be fixed ( ICZN, 1999). To best serve stability and universality of nomenclature I select to fix as the type species of Goniusa the taxonomic species actually involved in the misidentification (Article 70.3.2). The type species of the genus Goniusa Casey, 1906 is now fixed as Goniusa caseyi Gusarov , sp. n., misidentified as Euryusa obtusa LeConte, 1866 in the original description by Casey (1906).

Fenyes (1918) placed Goniusa in the subtribe Athetina and noted the similarity between Goniusa and the myrmecophilous genus Notothecta Thomson, 1858 ( Fenyes 1920) . Kistner (1976) disagreed with Fenyes and argued that based on "the structure of the maxillae with their setigerous lacinia and galea" Goniusa should be placed in Zyrini Bradley, 1930 (spelled as Zyrasini ), a junior synonym of Lomechusini Fleming, 1821 ( Newton & Thayer 1992). However, in Goniusa the galea is relatively short and it is only slightly projecting beyond the apex of lacinia ( Fig. 8) in comparison to the members of Lomechusini (e. g., Drusilla Leach in Samouelle, 1819 and Zyras Stephens, 1835 ; Figs. 16, 19). In Goniusa subapical setae of the internal margin of the galea are strong, and both galea and lacinia are very much like in other members of Athetini. Additionally, in Goniusa the mesosternal process is narrow and long ( Fig. 13) compared to the members of Lomechusini ( Figs. 17­18). Presented arguments confirm the view of Fenyes (1918): Goniusa is not related to Lomechusini and is a member of Athetini.

Both known species of Goniusa are associated with the ants of the genus Formica and have been collected inside the ant nests.