Geostiba
Creators: name: Gusarov, Vladimir I.
Publisher: name: Zenodo
Year: 2002
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Geostiba

description: Key for Identification of Nearctic Species of Geostiba
1 In males pronotum with one medial tubercle at posterior margin; each elytron with a tubercle near scutellum but not at the elytral suture; abdominal tergum 7 with one short medial carina in front of posterior margin. Posterior margin of female sternum 8 distinctly convex, without medial emargination. Aedeagus: Figs. 1­3 in Assing (2001). Spermatheca: Fig. 4 in Assing (2001). Body length 2.3­2.8 mm, pronotal width 0.43­0.53 mm. Introduced from Europe to Newfoundland (Fig. 336) ................ ......................................................................... 15. G. (s. str.) circellaris (Gravenhorst).
– In males pronotum without a medial tubercle at posterior margin; elytral suture is raised behind scutellum (flat in G. impressula); abdominal tergum 7 with two short and parallel medial carinae in front of posterior margin or without carinae. Posterior margin of female sternum 8 medially slightly concave or with emargination (Figs. 32­ 33, 54­55). Native Nearctic species ........................................................................... 2
2 Species occurring in eastern North America, east of the Rocky Mountains................. 3
– Species occurring in western North America, west of the Rocky Mountains ............ 15
3 Temples 2.3­2.7 times as long as eyes. Elytra (measured from humeral level) longer than pronotum. Wings fully developed. In males abdominal tergum 7 with two short and parallel medial carinae in front of posterior margin, abdominal tergum 8 with four short and weak carinae in front of posterior margin. Apex of median lobe in lateral view bent ventrally and widened apically (Figs. 36­37). Body length 1.9­2.4 mm, pronotal width 0.40­0.47 mm. Widely distributed in eastern North America from Mount Rogers, Virginia in the south to Maine, Québec and Wisconsin in the north (Fig. 337)................................................ 1. G. (Sibiota) appalachigena Gusarov, sp. n.
– Temples 2.7­6.0 times as long as eyes. Elytra shorter than pronotum. Wings reduced to short vestiges, shorter than elytra. Apex of median lobe of aedeagus has different shape. Distributed in the Southern Appalachians (North Carolina and Tennessee) (Figs. 337­338) ............................................................................................................ 4
4 Males (In males posterior margin of abdominal sternum 8 convex and without a fringe of wide setae (Fig. 30) and some species with two medial carinae on tergum 7) ....... 5
– Females (In females posterior margin of abdominal sternum 8 medially emarginate or concave, with a fringe of wide setae (Figs. 32­33, 54­55). Females never have carinae on abdominal terga 7­8). Females can be reliably identified only by association with males or by comparing locality data with known geographical distribution of different species of Geostiba.
5 Abdominal tergum 7 with two short and parallel medial carinae in front of posterior margin, tergum 8 with four short and weak carinae in front of posterior margin ....... 6
– Abdominal terga 7 and 8 without carina or tubercles ................................................ 12
6 Body length 1.9­2.3 mm, pronotal width 0.40­0.46 mm. Antennal segment 4 slightly transverse (width to length ratio about 1.2; Fig. 16). Apex of median lobe in ventral view broad (Figs. 57­58, 77­78) .................................................................................. 7
– Body length 1.6­2.3 mm, pronotal width 0.34­0.43 mm. Antennal segment 4 strongly transverse (width to length ratio about 1.6; Fig. 17). Apex of median lobe in ventral view narrow (Figs. 100­101, 126­127, 152­153) or broad (in G. balsamensis only, Figs. 193­194) ............................................................................................................. 8
7 Apex of median lobe of aedeagus in lateral view not bent ventrally (Figs. 59­60). Body length 2.0­ 2.3 mm, pronotal width 0.40­0.46 mm. Known from the Great Balsam Mountains and Little Pisgah Mountain in the Southern Appalachians(Figs. 338, 340) ...................................................................2. G. (Sibiota) bicarinata Lohse & Smetana
– Median lobe of aedeagus in lateral view bent ventrally (Figs. 79­80). Body length 1.9­ 2.3 mm, pronotal width 0.41­0.44 mm. Known from Graveyard Ridge and Black Balsam Knob in the Great Balsam Mountains – Pisgah Ridge massif in the Southern Appalachians (Figs. 338, 340) .............................. 3. G. (Sibiota) graveyardensis Pace
8 Apex of median lobe in ventral view broad (Figs. 193­194). Medial carinae on male tergum 7 weak. Body length 1.8­2.2 mm, pronotal width 0.36­0.39 mm. Known from the Plott Balsams – Cataloochee Divide massif in the Southern Appalachians (Figs. 338, 340) ................................................................... 8. G. (Sibiota) balsamensis Pace
– Apex of median lobe in ventral view narrow (Figs. 100­101, 126­127, 152­153). Medial carinae on male tergum 7 strong ..................................................................... 9
9 Apex of median lobe in lateral view with obtuse ventral projection (Figs. 176­177). Body length 1.8­2.3 mm, pronotal width 0.34­0.40 mm. Known from Snake Den Mountain in the Great Smoky Mountains massif (Figs. 338, 340) ................................................................................................7. G. (Sibiota) crepusculigena Gusarov, sp. n.
– Apex of median lobe in lateral view without obtuse ventral projection (Figs. 102­103, 128­129, 155­156) ..................................................................................................... 10
10 Apex of median lobe longer (Figs. 100­107), in ventral view the apex outline convex apically (Figs. 101, 105), in lateral view without denticle (Figs. 103, 107). Body length 1.6­2.0 mm, pronotal width 0.37­0.40 mm. Known from many localities in the Great Smoky Mountains massif (Figs. 338, 340) ..............................................................................................................................4. G. (Sibiota) nimbicola Lohse & Smetana
– Apex of median lobe shorter (Figs. 126­133, 152­156), in ventral view the apex outline often doubly emarginate (Figs. 131, 153­154), in lateral view with a denticle (Figs. 128­129, 155­156) ........................................................................................... 11
11 Apex of median lobe in lateral view with a strong ventral denticle (Figs. 155­156), in ventral view the apex outline strongly doubly emarginate (Figs. 152­154). Body
length 1.6­1.9 mm, pronotal width 0.37­0.40 mm. Known from many localities in the Great Smoky Mountains massif (Figs. 338, 340) .......................................................... ...................................................................... 6. G. (Sibiota) nebuligena Gusarov, sp. n. – Apex of median lobe in lateral view with a weak ventral denticle (Figs. 128­129), in ventral view the apex outline weakly doubly emarginate (Figs. 130­131) or convex (Figs. 126­127, 132­133). Body length 1.9­2.2 mm, pronotal width 0.36­0.43 mm. Known from the Plott Balsams – Cataloochee Divide massif in the Southern Appalachians (Figs. 338, 340) .................................. 5. G. (Sibiota) pluvigena Gusarov, sp. n.
12 Body length 1.8­2.2 mm, pronotal width 0.34­0.39 mm. Lateral sides of the apex of median lobe with shallow emargination (in ventral view) (Figs. 219­220, 223­229, 249­250) ..................................................................................................................... 13
– Body length 1.9­2.6 mm, pronotal width 0.39­0.44 mm. Lateral sides of the apex of median lobe with deep emargination (in ventral view) (Figs. 267­268, 289­291) ..... 14
13 Median lobe of aedeagus in ventral view more narrow (Figs. 219­220, 223­229). Distal diverticula of internal sac long (Figs. 233­234), proximal diverticula small (Fig. 234). Body length 1.8­2.2 mm, pronotal width 0.34­0.39 mm. Known from the Great Balsam Mountains – Pisgah Ridge massif and from Standing Indian in the Blue Ridge in the Southern Appalachians (Figs. 338, 340) .............................................................. .................................................................... 9. G. (Sibiota) nubigena Lohse & Smetana
– Median lobe of aedeagus in ventral view wider (Figs. 249­250). Distal diverticula of internal sac short and small (Figs. 253, 256), proximal diverticula very large (Figs. 253, 257­258). Body length 1.8­1.9 mm, pronotal width 0.34 mm. Known only from the Great Smoky Mountains west of Clingmans Dome (Figs. 338, 340) ...................... ..................................................................... 10. G. (Sibiota) coeligena Gusarov, sp. n.
14 Median lobe of aedeagus longer (Fig. 269), in lateral view more narrow (Figs. 269­ 270), in ventral view the lateral sides of the apex less convex (Figs. 267­268). Body length 1.9­2.4 mm, pronotal width 0.39­0.44 mm. Known only from the Great Craggy Mountains and the Black Mountains in the Southern Appalachians (Figs. 338­339) .... ..................................................................... 11. G. (Sibiota) alticola Lohse & Smetana
– Median lobe of aedeagus shorter (Fig. 292), in lateral view broader (Figs. 292­293), in ventral view the lateral sides of the apex more convex (Figs. 289­291). Body length 2.2­2.6 mm, pronotal width 0.40­0.44 mm. Known only from Roan Mountain and the Big Bald (Bald Mountains) in the Southern Appalachians (Figs. 338­339) .................. ................................................................................... 12. G. (Sibiota) carteriensis Pace
15 Elytra (measured from humeral level) shorter than pronotum. Wings reduced, shorter than elytra. In males pronotum with strong, wide and deep impression along midline. Median lobe of aedeagus with wider apex (in ventral view) (Figs. 310­312, 315). Body length 2.2­2.7 mm, pronotal width 0.37­0.50 mm. Known from Oregon (Fig. 336) ................................................................................ 13. G. (Sibiota) impressula (Casey)
– Elytra as long as pronotum. Wings fully developed. In males pronotum without deep impression along midline. Median lobe of aedeagus with more narrow apex (in ventral view (Figs. 323­324). Body length 2.4 mm, pronotal width 0.41 mm. Known from California (Fig. 336)............................ 14. G. (Sibiota) silvigena Gusarov, sp. n.
description: Published as part of Gusarov, Vladimir I., 2002, A revision of Nearctic species of the genus Geostiba Thomson, 1858 (Coleoptera: Staphylinidae: Aleocharinae), pp. 1-88 in Zootaxa 81 on pages 15-17, DOI: 10.5281/zenodo.155701