Geostiba (Sibiota) balsamensis 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 : 47-52

8. Geostiba (Sibiota) balsamensis Pace, 1997 ( Figs. 187­212 )

Geostiba (Lioglutosipalia) balsamensis Pace, 1997: 104 .

Material. UNITED STATES: North Carolina: Swain Co.: 8 specimens, SW slope of Cataloochee Balsam Mt., Balsam Mt. Road, 20 km NW Waynesville, 35°34.3'N 83°10.9'W, 1700 m, in forest litter, Picea rubens , Acer , Fagus , Betula (V.I.Gusarov) , 2.vi.2001; 3 specimens, Balsam Mt. Road, 17 km NWW Waynesville, 35°32.79'N 83°10.0'W, 1650 m, in forest litter, Picea rubens , Abies fraseri , Fagus , Betula (V.I.Gusarov) , 2.vi.2001; Swain Co. / Haywood Co.: 2 specimens, Balsam Mt. Road, Masonic Monument, 17 km NWW Waynesville, 35°32.2'N 83°10.2'W, 1400 m, in forest litter, Tsuga , Acer , Rhododendron (V.I.Gusarov) , 2.vi.2001; Haywood Co. / Jackson Co.: 5 specimens, junction of Balsam Mt. Road and Blue Ridge Parkway, 17 km W Waynesville, 35°29.72'N 83°10.43'W, 1600 m, in forest litter, Picea rubens , Fagus , Betula , Rhododendron (V.I.Gusarov) , 2.vi.2001 (all in KSEM);, N slope of Waterrock Knob, 13 km W Waynesville, 35°28.0'N 83°08.2'W, 1900 m, in forest litter, Picea rubens , Abies fraseri (V.I.Gusarov) , 2.vi.2001 ( SPSU); Haywood Co.:, Blue Ridge Parkway, 15 km W Waynesville, 35°30.34'N 83°09.34'W, 1350 m, in forest litter (V.I.Gusarov), 20.viii.1998 ( SPSU).

Type locality. UNITED STATES: North Carolina: Swain Co.: Cataloochee Balsam Mt., Heintooga overlook ( Pace 1997). Pace cites this locality as “Heintoge Overlot”. This is one of the parking overlooks at the Heintooga spur of the Blue Ridge Parkway (Balsam Mountain Road).

Diagnosis. Geostiba balsamensis can be distinguished from other Nearctic species of Geostiba by having small eyes (temple length to eye length ratio 3.0­3.7), pronotal pubescence of type V, reduced wings, short elytra (pronotum length to elytron length ratio 1.4), the presence of two weak and short parallel carinae in the middle of abdominal tergum 7 in front of posterior margin, the shape of the aedeagus ( Figs. 193­202 , 204­212 ) and the shape of the spermatheca ( Fig. 203 ).

Geostiba balsamensis differs from G. nubigena in having two week carinae on male tergum 7 and wider apex of median lobe ( Figs. 193­194 , 219­220, 223­229 ).

Description. Length 1.8­2.2 mm. Body and antennae brownish yellow to light brown, legs and mouthparts brownish yellow. 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 3.0­3.8. Antennal article 2 longer than article 3, articles 4­10 transverse to strongly transverse, last article as long as 9 and 10 combined.

Pronotum as wide as long, width 0.36­0.39 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 (1.6), with fine isodiametric microsculpture and fine asperate puncturation, distance between punctures equals 2­3 times their diameter. Elytral suture behind scutellum slightly raised in both sexes. 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 with two very weak medial carinae in front of posterior margin. Posterior margin of male tergum 8 and sternum 8 convex ( Figs. 187­188 ).

Female tergum 8 with convex posterior margin ( Fig. 189 ), posterior margin of female sternum 8 concave medially ( Figs. 190­191 ).

Aedeagus as in Figs. 193­202 , 204­212 . Apex of median lobe in ventral view broad ( Figs. 193­194 ), in lateral view strait ( Figs. 195­196 ).

CP – copulatory piece, DD – distal diverticula of internal sac, LW – lateral wall of internal sac, ML – medial lamellae, PD – proximal diverticula of internal sac.

Spermatheca as in Fig. 203 .

Distribution. Known from the Plott Balsams – Cataloochee Divide massif (North Carolina) ( Figs. 338 , 340 ).

Natural History. Geostiba balsamensis was collected at altitudes of 1300­1900 m in leaf litter in pure conifer or mixed forest with red spruce ( Picea rubens ), Fraser’s fir ( Abies fraseri ) or hemlock.

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 187 ­ 192. Abdominal segments 7 ­ 8 of Geostiba balsamensis Pace (Cataloochee Balsam Mountain, North Carolina). 187 – male tergum 8; 188 – male sternum 8; 189 – female tergum 8; 190 – female sternum 8, 191 – apex of female sternum 8; 192 – medial portion of male tergum 7, posterior down. Scale bar 0.2 mm (187 ­ 190, 192), 0.1 mm (191).

FIGURES 193 ­ 196. Aedeagus of Geostiba balsamensis Pace (Cataloochee Balsam Mountain, North Carolina). 193 – median lobe, ventral view; 194 – apex of median lobe, ventral view; 195 – median lobe, lateral view; 196 – apex of median lobe, lateral view. Scale bar 0.2 mm (193, 195), 0.1 mm (194, 196).

FIGURES 197 ­ 203. Genitalia of Geostiba balsamensis Pace (Cataloochee Balsam Mountain, North Carolina). 197 – details of internal sac retracted into median lobe, ventral view; 198 – everted internal sac, ventral view; 199 – completely everted internal sac, ventral view; 200 – copulatory piece of internal sac, dorsal view; 201 – medial lamellae of internal sac, ventral view; 202 – distal diverticula of everted internal sac, ventral view; 203 – spermatheca. Scale bar 0.2 mm (197 ­ 199), 0.1 mm (200 ­ 203). CP – copulatory piece, DD – distal diverticula of internal sac, LW – lateral wall of internal sac, ML – medial lamellae, PD – proximal diverticula of internal sac, S – suspensoria, UP – U­shaped plate.

FIGURES 204 ­ 212. Aedeagus of Geostiba balsamensis Pace (Cataloochee Balsam Mountain, North Carolina). 204 ­ 206 – details of internal sac retracted into median lobe, lateral view; 207 – copulatory piece of internal sac, lateral view; 208 – medial lamella of internal sac, lateral view; 209 – everted internal sac, lateral view; 210 – completely everted internal sac, lateral view; 211 – right distal diverticulum of everted internal sac, lateral view; 212 – apex of left paramere, side facing median lobe. Scale bar 0.2 mm (204 ­ 206, 209 ­ 210), 0.1 mm (207 ­ 208, 211 ­ 212).

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).