Geostiba (Sibiota) deliqua, Assing, 2018

Assing, Volker, 2018, A revision of Geostiba of the West Palaearctic region. XXVI. New species and additional records, primarily from the Caucasus region (Coleoptera: Staphylinidae: Aleocharinae), Linzer biologische Beiträge 50 (2), pp. 1033-1054: 1043-1047

publication ID

http://doi.org/10.5281/zenodo.3776388

DOI

http://doi.org/10.5281/zenodo.3796520

persistent identifier

http://treatment.plazi.org/id/472287CC-B51C-3C5F-1AC4-1AB4FE01FB19

treatment provided by

Valdenar

scientific name

Geostiba (Sibiota) deliqua
status

nov.sp.

Geostiba (Sibiota) deliqua   nov.sp. ( Figs 36-42 View Figs 36-42 , 44 View Figs 43-44 ; Map 2 View Map 2 )

T y p e m a t e r i a l: Holotype ♂: " ARMENIA [27] – WSW Kapan , W Kajaran, 39°09'22''N, 46°06'13''E 2050 m, mixed forest, 10.VII.2018, V. Assing / Holotypus ♂ Geostiba deliqua   sp. n. det. V. Assing 2018" (cAss) GoogleMaps   . Paratypes: 2♂♂: same data as holotype (cAss) GoogleMaps   ; 1♀: same data, but leg. Schülke ( MNB) GoogleMaps   .

E t y m o l o g y: The specific epithet (Latin, adjective: missing, absent) alludes to the unmodified male tergite VII.

D e s c r i p t i o n: Body length 2.2-2.3 mm; length of forebody 0.8-0.9 mm. Habitus as in Fig. 36 View Figs 36-42 . Coloration: body yellowish to reddish-yellow with the middle of abdominal segment VI slightly darker; legs and antennae pale-yellow. Eyes strongly reduced, composed of 3-4 ommatidia and with weak pigmentation ( Fig. 37 View Figs 36-42 ). Other external characters not distinctive.

♂: elytra ( Fig 37 View Figs 36-42 ) extensively and moderately deeply impressed, suture distinctly and broadly elevated near scutellum, posteriorly extending into a narrow keel; tergite VII unmodified, without tubercles or keel; median lobe of aedeagus 0.23 mm long and shaped as in Figs 38-41 View Figs 36-42 .

♀: spermatheca as in Fig. 42. View Figs 36-42

C o m p a r a t i v e n o t e s: This species is distinguished from most other Armeni- an representatives of the subgenus Sibiota   by small body size, pale coloration, and particularly by the unmodified male tergite VII. Using the key in ASSING (2017a), G. deliqua   would key out at couplet 3, together with G. immutata ASSING, 2017 from the environs of Tatev (south of Goris), the only other Armenian Sibiota   species without tubercles or keels on the male tergite VII. The new species differs from G. immutata by even smaller size, on average paler coloration, even smaller eye rudiments with fewer ommatidia (G. immutata: eyes composed of approximately 6 ommatidia), much more distinctly modified male elytra (G. immutata: without impressions; suture not elevated, with few granules on either side at most), by the shape of the smaller median lobe of the aedeagus (G. immutata: median lobe 0.24-0.25 mm long; ventral process more strongly curved in lateral view; crista apicalis smaller), and by the shape of the spermatheca.

Geostiba deliqua   is evidently very closely allied to G. unicuneata   , as can be inferred from the highly similar external characters (coloration, body size, eye size), from the similar modifications of the male elytra, the similar structure of the aedeagus, and from the similar shape of the spermatheca. Aside from the complete absence of the median keel on the male tergite VII, G. deliqua   is distinguished from G. unicuneata   only by a slightly larger median lobe of the aedeagus ( G. unicuneata   : median lobe usually 0.21- 0.22 mm long) with the apex of the ventral process of slightly different shape and with an on average slightly larger crista apicalis. Despite the similarity of the primary sexual characters, it seems rather unlikely that G. deliqua   is conspecific with G. unicuneata   . First, the primary sexual characters are generally rather uniform in Armenian Sibiota   ; for instance, the spermathecae of G. nigrohortensia   and G. unicuneata   are of practically identical shape, although these species are readily distinguished based on external characters alone. Second, the 36 males of G. unicuneata   that have been examined so far have the median keel on tergite VII at least indicated, whereas this keel is completely absent in all three males of G. deliqua   . Third, in males of G. unicuneata   with a median keel of reduced size the elytral modifications are usually reduced, too. Finally, the slight differences in the shape of the apex of the ventral process of the aedeagus appear to be constant.

D i s t r i b u t i o n a n d n a t u r a l h i s t o r y: The type locality is situated near Kajaran, west-southwest of Kapan, South Armenia ( Map 2 View Map 2 ), at an altitude of 2050 m. The type specimens were sifted from litter and grass roots in a montane mixed deciduous forest ( Fig. 44 View Figs 43-44 ).

T

Tavera, Department of Geology and Geophysics

V

Royal British Columbia Museum - Herbarium