Geostiba (Sibiota) carteriensis Pace, 1997

Gusarov, Vladimir I., 2002, A revision of Nearctic species of the genus Geostiba Thomson, 1858 (Coleoptera: Staphylinidae: Aleocharinae), Zootaxa 81, pp. 1-88 : 64-68

12. Geostiba (Sibiota) carteriensis Pace, 1997 ( Figs. 284­305 )

Geostiba (Lioglutosipalia) carteriensis Pace, 1997: 106 , ex parte.

Type material. Two paratypes of G. carteriensis belong to G. alticola : 2, Yancey Co.: Mt. Mitchell, 1800 m (P.Debs), 17.iv.1974 (not examined). My collecting demonstrated that these paratypes originate from the mountain massif where G. carteriensis does not occur. These presumably misidentified paratypes belong to G. alticola .

Material. UNITED STATES: Tennessee / North Carolina: Carter Co. / Mitchell Co.: 12 specimens, 29 km SSE Elizabethton, Roan Road Pass, Rd. 143/261, 36°06.3'N 82°06.8'W, 1700 m, in forest litter and moss, Picea , Rhododendron (V.I.Gusarov) , 17.iii.2001; Unicoi Co. / Yancey Co.: 12 specimens, 9 km E Lewisburg, Big Bald, 35°59.57'N 82°29.61'W, 1650 m, meadows, in grass (V.I.Gusarov), 21.ix.2001 (all ­ KSEM and SPSU).

Type locality. UNITED STATES: Tennessee / North Carolina: Carter Co. / Mitchell Co.: Roan Mountain, Forest Road 130, 6300’ ( Pace 1997).

Diagnosis. Geostiba carteriensis can be distinguished from other Nearctic species of Geostiba by having small eyes (temple length to eye length ratio 3.8­4.6), pronotal pubescence of type V or VI, pronotal pubescence directed posteriorly in a wide medial zone (wider in males), not just along the midline, reduced wings, short elytra (pronotum length to elytron length ratio 1.3), the absence of carinae on abdominal tergum 7, the shape of the aedeagus ( Figs. 289­298, 300­305 ) and the shape of the spermatheca ( Fig. 299 ).

Geostiba carteriensis differs from closely related G. alticola in having shorter and wider (in lateral view) apex of the aedeagus median lobe ( Figs. 292­293 , 269­270 ) and the lateral sides of the apex more convex (in ventral view) ( Figs. 289­291 , 267­268 ).

Description. Length 2.2­2.6 mm. Body uniformly yellowish brown, in some specimens abdominal segments 3­6 darker. Body parallel­sided.

Head as wide as long, surface on disk with fine isodiametric microsculpture, puncturation very fine, distance between punctures equal to 2­4 times their diameter. Temple length to eye length ratio 3.8­4.6. Antennal article 2 longer than article 3, article 4 subquadrate, articles 5­10 transverse, last article as long as 9 and 10 combined.

Pronotum as wide as long, width 0.40­0.44 mm, wider than head (pronotal width to head width ratio 1.1); microsculpture and puncturation as on head; pronotal pubescence of type V or VI, directed posteriorly in wide medial zone (wider in males), not just along midline. Elytra measured from humeral angle shorter than pronotum (pronotal length to elytral length ratio 1.3), 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 2­5 times their diameter. Tergum 7 without white edge.

Males with stronger impression on disc of head and along midline of pronotum than females. Male tergum 7 without carinae. Posterior margin of male tergum 8 slightly convex ( Fig. 284 ). Posterior margin of male sternum 8 convex ( Fig. 285 ).

Posterior margin of female tergum 8 convex ( Fig. 286 ). Posterior margin of female sternum 8 concave medially ( Figs. 287­288 ).

Aedeagus as in Figs. 289­298, 300­305 . Apex of median lobe in lateral view strait ( Figs. 292­293 ), in ventral view apex outline strongly emarginate basally ( Figs. 289­291 ). Distal diverticula of internal sac narrow ( Figs. 297­298, 304 ).

Spermatheca as in Fig. 299 .

Distribution and variability. Known only from the Big Bald in the Bald Mountains massif and from Roan Mountains ( Figs. 338­339 ). Specimens from the Big Bald and from Roan High Knob (the type locality) slightly differ in the shape of the apex of median lobe ( Figs. 289­290 ) and may deserve to be interpreted as distinct taxa. More samples from the adjacent mountains (especially north of Roan Mountains) are necessary to resolve this problem.

Natural History. Geostiba carteriensis was collected in forest litter at altitudes above 1600 m in leaf litter of coniferous forest with red spruce ( Picea rubens ) and in the soil of a mountain meadow (a “bald”).

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 339. Detailed geographical distribution of Geostiba alticola Lohse & Smetana (11) and G. carteriensis Pace (12) in the Southern Appalachians. Isohypses 1200 m and 1500 m are shown. Areas above 1500 m are solid black.

FIGURES 284 ­ 288. Abdominal segment 8 of Geostiba carteriensis Pace (Roan Road Pass, Tennessee / North Carolina). 284 – male tergum 8; 285 – male sternum 8; 286 – female tergum 8; 287 – female sternum 8, 288 – apex of female sternum 8. Scale bar 0.2 mm (284 ­ 287), 0.1 mm (288).

FIGURES 289 ­ 293. Aedeagus of Geostiba carteriensis Pace (Big Bald (289) and Roan Road Pass (290 ­ 293), Tennessee / North Carolina). 289 ­ 290 – median lobe, ventral view; 291 – apex of median lobe, ventral view; 292 – median lobe, lateral view; 293 – apex of median lobe, lateral view. Scale bar 0.2 mm (289 ­ 290, 292), 0.1 mm (291, 293).

FIGURES 294 ­ 305. Genitalia of Geostiba carteriensis Pace (Roan Road Pass, Tennessee / North Carolina). 294 – details of internal sac retracted into median lobe, ventral view; 295 – copulatory piece of internal sac, dorsal view; 296 – medial lamellae of internal sac, ventral view; 297 – distal diverticula of everted internal sac, ventral view; 298 – everted internal sac, ventral view; 299 – spermatheca; 300 ­ 301 – details of internal sac retracted into median lobe, lateral view; 302 – copulatory piece of internal sac, lateral view; 303 – everted internal sac, lateral view; 304 – right distal diverticulum of everted internal sac, lateral view; 305 – apex of left paramere, side facing median lobe. Scale bar 0.2 mm (294, 298, 300 ­ 301, 303), 0.1 mm (295 ­ 297, 299, 302, 304 ­ 305).

FIGURES 267 ­ 270. Aedeagus of Geostiba alticola Lohse & Smetana (N slope of Mt. Mitchell, North Carolina). 267 – median lobe, ventral view; 268 – apex of median lobe, ventral view; 269 – median lobe, lateral view; 270 – apex of median lobe, lateral view. Scale bar 0.2 mm (267, 269), 0.1 mm (268, 270).