A revision of Nearctic species of the genus Geostiba Thomson, 1858 (Coleoptera: Staphylinidae: Aleocharinae)
Author
Gusarov, Vladimir I.
text
Zootaxa
2002
81
1
88
journal article
51429
10.5281/zenodo.155701
b947e6c9-d6cf-4988-a098-5e01dd69a888
11755326
155701
5.
Geostiba
(
Sibiota
)
pluvigena
Gusarov
,
sp. n.
(
Figs. 120145
)
Geostiba bicarinata
:
Lohse & Smetana, 1988
: 273
,
ex parte
(misidentification).
Type
material.
Holotype
,,
UNITED STATES
: North Carolina:
Haywood Co. / Jackson Co.: junction of Blue Ridge Parkway and Balsam Mountain Road,
17 km
W Waynesville,
35°29.72'N
83°10.43'W
,
1600 m
, in forest litter,
Picea rubens
,
Fagus grandifolia
,
Betula
,
Rhododendron
,
Maianthemum canadense
,
Oxalis
(V.I.Gusarov)
,
2.vi.2001
(
KSEM
).
FIGURES 120125
. Abdominal segments 78 of
Geostiba pluvigena
Gusarov
,
sp. n.
(paratypes from Waterrock Knob (120121, 125) and junction of Blue Ridge Parkway and Balsam Mountain Road (122124), North Carolina). 120 – male tergum 8; 121 – male sternum 8; 122 – female tergum 8; 123 – female sternum 8, 124 – apex of female sternum 8; 125 – medial portion of male tergum 7, posterior down. Scale bar 0.2 mm (120123, 125), 0.1 mm (124).
Paratypes
:
UNITED STATES
: North Carolina:
Haywood Co. / Jackson Co.:
99 specimens
, same data as the
holotype
(
KSEM
,
AMNH
,
CNCI
,
SPSU
,
FMNH
);
43 specimens
, Waterrock Knob, N slope,
13 km
W Waynesville,
35°28.0'N
83°08.2'W
,
1900 m
, in forest litter,
Picea rubens
,
Abies fraseri
,
Rubus
,
Oxalis
(V.I.Gusarov)
,
2.vi.2001
(
KSEM
,
SPSU
); Haywood Co.:, Blue Ridge Parkway, Browning Knob Mt. [
35°27'47"N
83°07'55"W
],
18301890 m
(A.Smetana),
28.v.1986
(
Lohse and Smetana (1988)
listed this specimen as a
paratype
in the
type
series of
G. bicarinata
)(
CNCI
).
FIGURES 126133
. Aedeagus of
Geostiba pluvigena
Gusarov
,
sp. n.
(paratypes from the junction of Blue Ridge Parkway and Balsam Mountain Road (126129, 132133) and Waterrock Knob (130 131), North Carolina). 126, 130, 132 – median lobe, ventral view; 127, 131, 133 – apex of median lobe, ventral view; 128 – median lobe, lateral view; 129 – apex of median lobe, lateral view. Scale bar 0.2 mm (126, 128, 130, 132), 0.1 mm (127, 129, 131, 133).
Diagnosis.
Geostiba pluvigena
can be distinguished from other Nearctic species of
Geostiba
by having small eyes (temple length to eye length ratio 2.73.8), pronotal pubescence of
type
V, reduced wings, short elytra (pronotum length to elytron length ratio 1.3), the presence of two short parallel carinae in the middle of abdominal tergum
7 in
front of posterior margin, the shape of the aedeagus (
Figs. 126138, 140145
) and the shape of the spermatheca (
Fig. 139
).
Geostiba pluvigena
is closely related to
G. nimbicola
,
G. nebuligena
and
G. crepusculigena
.
Geostiba pluvigena
differs from
G. nimbicola
in having shorter and broader (in ventral view) apex of median lobe with weak apical denticle (in lateral view) (
Figs. 126 133
,
100107
); from
G. nebuligena
in having weaker apical denticle of median lobe of aedeagus (
Figs. 128129
,
155156
); from
G. crepusculigena
in lacking obtuse projection on the ventral side of the apex of median lobe (
Figs. 128129
,
176177
).
Description.
Length
1.92.2 mm
. Brown, pronotum, elytra and apex of abdomen often lighter, antennae brownish yellow or 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 34 times their diameter. Temple length to eye length ratio 2.73.8. Antennal article 2 longer than article 3, article 4 transverse (width to length ratio 1.6), articles 510 strongly transverse (ratio 1.71.9), last article as long as 9 and 10 combined (
Fig. 17
).
Pronotum as wide as long, width
0.360.43 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 1.3), 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 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 25 times their diameter. Tergum 7 without white edge.
Male tergum 7 with two medial carinae in front of posterior margin. Male tergum 8 with two or four weak and short carinae in front of posterior margin, posterior margin convex (
Fig. 120
). Male sternum 8 with convex posterior margin (
Fig. 121
).
Female tergum 8 with convex posterior margin (
Fig. 122
), sternum 8 with emarginate posterior margin (
Figs. 123124
).
Aedeagus as in
Figs. 126138, 140145
. Apex of median lobe in ventral view narrow, its outline convex or doubly emarginate apically (
Figs. 126127, 130133
), in lateral view strait, with weak apical denticle ventrally (
Figs. 128129
), distal diverticula of internal sac in ventral view broad (
Figs. 137138
).
Spermatheca as in
Fig. 139
.
Distribution.
Known from the Plott Balsams – Cataloochee Divide massif (North Carolina) (
Figs. 338
,
340
).
Natural History.
Geostiba nimbicola
was collected at altitudes above
1600 m
in leaf litter in mixed forest with red spruce (
Picea rubens
).
Etymology.
The specific name is derived from the Latin adjective
pluvius
(rainy) and the verb
gigno
(to be born, to arise). It refers to the rains in the Southern Appalachians where the species occurs.