Geostiba (Sibiota) coeligena Gusarov

Gusarov, Vladimir I., 2002, A revision of Nearctic species of the genus Geostiba Thomson, 1858 (Coleoptera: Staphylinidae: Aleocharinae), Zootaxa 81, pp. 1-88 : 57-59

10. Geostiba (Sibiota) coeligena Gusarov , sp. n. ( Figs. 247­261 )

Type material. Holotype ,, UNITED STATES: Tennessee / North Carolina: Sevier Co. / Swain Co.: Appalachian National Scenic Trail, W of Clingmans Dome, 16 km S Gatlinburg, 35°33.88'N 83°31.41'W, 1930 m, in forest litter, Picea , Abies , Betula , Oxalis (V.I.Gusarov) , 22.vi.2001 ( KSEM).

Paratype:, as the holotype but 35°33.74'N 83°30.84'W, 1950 m, in forest litter, Abies , Vaccinium , Oxalis ( SPSU).

Diagnosis. Geostiba coeligena can be distinguished from other Nearctic species of Geostiba by having small eyes (temple length to eye length ratio 4.0­5.6), pronotal pubescence of type V, reduced wings, short elytra (pronotum length to elytron length ratio 1.4), the absence of carinae on abdominal tergum 7 and the shape of the aedeagus ( Figs. 249­ 261 ).

Geostiba coeligena differs from G. balsamensis in lacking the carinae on male tergum 7; from G. nubigena in having broader median lobe of aedeagus (in ventral view) ( Figs. 249­250 , 219­220, 223­229 ), short distal diverticula ( Figs. 253, 256 , 233­234 ) and large proximal diverticula of internal sac ( Figs. 253, 257­258 , 234 ).

Description. Length 1.8­1.9 mm. Body brownish yellow to brown, antennae light brown, mouthparts and legs brownish yellow. Body parallel­sided.

Head as wide as long, surface on disk with fine isodiametric microsculpture, puncturation very fine, distance between punctures equal to 3­4 times their diameter. Temple length to eye length ratio 4.0­5.6. Antennal article 2 longer than article 3, article 4­10 transverse to strongly transverse, last article as long as 9 and 10 combined.

Pronotum as wide as long, width 0.34 mm, wider than head (pronotal width to head width ratio 1.1); microsculpture and puncturation as on head. Pronotal pubescence of type V. Elytra measured from humeral angle shorter than pronotum (pronotal length to elytral length ratio 1.4), wider than long (1.5), with fine isodiametric microsculpture and fine asperate puncturation, distance between punctures equals 2­3 times their diameter. Elytral suture behind scutellum very slightly raised. Wings reduced to short vestiges, shorter than elytra.

Abdominal terga with fine microsculpture of transverse meshes, with fine and sparse puncturation, puncturation becoming finer towards abdomen apex, on terga 3­5 distance between punctures equals 3­6 times their diameter. Tergum 7 without white edge.

Male tergum 7 without carinae. Posterior margin of male tergum 8 and sternum 8 convex ( Figs. 247­248 ).

Aedeagus as in Figs. 249­261 . Apex of median lobe in lateral view strait ( Figs. 251­ 252 ).

Female unknown.

Distribution. Known from the Great Smoky Mountains massif west of Clingmans Dome ( Figs. 338 , 340 ).

Natural History. Geostiba coeligena was collected in forest litter at altitudes above 1900 m in leaf litter mostly in coniferous forest with Fraser’s fir ( Abies fraseri ) and red spruce ( Picea rubens ).

Etymology. The specific name is derived from the Latin noun coelum (the sky, the heavens) and the verb gigno (to be born, to arise). It refers to the high mountains where the species occurs.

Figures

FIGURE 338. Geographical distribution of twelve species of Geostiba in the Southern Appalachians. Isohypses 1200 m and 1500 m are shown. Areas above 1500 m are solid black.

FIGURE 340. Detailed geographical distribution of Geostiba bicarinata Lohse & Smetana (2), G. graveyardensis Pace (3), G. nimbicola Lohse & Smetana (4), G. pluvigena Gusarov, sp. n. (5), G. nebuligena Gusarov, sp. n. (6), G. crepusculigena Gusarov, sp. n. (7), G. balsamensis Pace (8), G. nubigena Lohse & Smetana (9), G. coeligena Gusarov, sp. n. (10) in the Southern Appalachians. Isohypses 1200 m and 1500 m are shown. Areas above 1500 m are solid black.

FIGURES 247 ­ 252. Abdominal segment 8 and aedeagus of Geostiba coeligena Gusarov, sp. n. (paratype). 247 – male tergum 8; 248 – male sternum 8; 249 – median lobe, ventral view; 250 – apex of median lobe, ventral view; 251 – median lobe, lateral view; 252 – apex of median lobe, lateral view. Scale bar 0.2 mm (247 ­ 249, 251), 0.1 mm (250, 252).

FIGURES 253 ­ 261. Aedeagus of Geostiba coeligena Gusarov, sp. n. (253, 256 ­ 258, 260 ­ 261 – paratype, 254 ­ 255, 259 ­ holotype). 253 – everted internal sac, ventral view; 254 – copulatory piece of internal sac, dorsal view; 255 – medial lamellae of internal sac, ventral view; 256 – distal diverticula of everted internal sac, ventral view; 257 – left proximal diverticulum of everted internal sac, ventral view; 258 – everted internal sac, lateral view; 259 – copulatory piece of internal sac, lateral view; 260 – medial lamella of internal sac, lateral view; 261 – apex of left paramere, side facing median lobe. Scale bar 0.2 mm (253, 258), 0.1 mm (254 ­ 257, 259 ­ 261).

FIGURES 219 ­ 229. Aedeagus of Geostiba nubigena Lohse & Smetana (Richland Balsam Mountain (219 ­ 222), Blue Ridge Parkway (223), Graveyard Fields (224 ­ 227) and Grassy Ridge Mine Overlook (228 ­ 229), North Carolina). 219, 224, 226, 228 – median lobe, ventral view; 220, 223, 225, 227, 229 – apex of median lobe, ventral view; 221 – median lobe, lateral view; 222 – apex of median lobe, lateral view. Scale bar 0.2 mm (219, 221, 224, 226, 228), 0.1 mm (220, 222 ­ 223, 225, 227, 229).

FIGURES 230 ­ 246. Genitalia of Geostiba nubigena Lohse & Smetana (Richland Balsam Mountain (230 ­ 231, 234 ­ 235, 237 ­ 238, 242, 246) and Blue Ridge Parkway (232 ­ 233, 236, 239 ­ 241, 243 ­ 245), North Carolina). 230 – details of internal sac retracted into median lobe, ventral view; 231 – copulatory piece of internal sac, dorsal view; 232 – medial lamellae of internal sac, ventral view; 233 – distal diverticula of everted internal sac, ventral view; 234 – everted internal sac, ventral view; 235 ­ 236 – spermatheca; 237 ­ 238 – details of internal sac retracted into median lobe, lateral view; 239 – partially everted internal sac, lateral view; 240 – details of internal sac inside partially everted internal sac, lateral view; 241 – everted internal sac, lateral view; 242 – completely everted internal sac, lateral view; 243 – copulatory piece of internal sac, lateral view; 244 – medial lamella of internal sac, lateral view; 245 – right distal diverticulum of everted internal sac, lateral view; 246 – apex of left paramere, side facing median lobe. Scale bar 0.2 mm (230, 234, 237 ­ 242), 0.1 mm (231 ­ 233, 235 ­ 236, 243 ­ 246).