Atheta (Microdota) monroe Klimaszewski and Chandler, 2023

Klimaszewski, Jan, Chandler, Donald S., Davies, Anthony & Bourdon, Caroline, 2023, Aleocharine rove beetles of New Hampshire, USA: new taxa and new records (Coleoptera, Staphylinidae, Aleocharinae), Zootaxa 5364 (1), pp. 1-141 : 32-33

54. Atheta (Microdota) monroe Klimaszewski and Chandler sp. n.

Figs. 4a – h , Table 1

Holotype (male). USA, New Hampshire, Coos Co.: Mt. Washington, Lakes of the Clouds , 5000’, 10.IX.1987, A. Smetana ( CNC). Paratypes: USA, New Hampshire, Coos Co.: Mt. Monroe, around Lakes of the Clouds , 5000– 5100’, 10.IX.1987, J.M. Campbell and A. Davies, Vaccinium , dwarf Betula , leatherleaf litter near lake ( CNC), 4 males, 4 females, 2 sex? Mt. Washington above tree line, 5200–5700’, 10.IX.1987, J.M. Campbell and A. Davies, dwarf Salix , Vaccinium , leatherleaf litter ( CNC), 3 males, 5 females, 34 sex? Mt. Washington, Alpine Garden, 5300’, 12.IX.1987, J.M. Campbell and A. Davies, sifting dwarf Betula litter ( CNC), 4 males, 47 sex? Mt. Washington, Auto Rd., 4100’, 14.IX.1987, sifting Sphagnum under spruce tree near spring ( CNC), 1 sex? Mt. Jefferson, Caps Ridge trail, 4800’ (error on label 14800’), 11.IX.1987, A. Smetana ( CNC), 1 sex? Mt. Washington, above tree line, 5300–5700’, 10.IX.1987, J.M. Campbell and A. Davies, dwarf Salix , Vaccinium , leatherleaf litter ( CNC), 3 males, 1 female. Mt. Washington, Lakes of the Clouds, 5000’, 10.IX.1987, A. Smetana ( CNC), 3 male, 2 females, 1 sex? Mt. Jefferson Caps Ridge Trail, 4800’, A. Smetana ( CNC), 2 sex? CANADA, Quebec, Gaspesie Park, Lac du Diable, 12.VII.1972, 1500’, J.M. and B.A. Campbell ( CNC), 1 male. Mare-du-Sault, Parc des Laurentides, 2700’, 15–17.VII.1970, J.M. and B.A. Campbell ( CNC), 1 male .

Etymology. The specific name ‘monroe’ is a name in apposition derived from Mt. Monroe, NH, where some specimens of the type series were captured.

Diagnosis. Distinguishable by its small and narrowly elongate body, 2.0–2.6 mm long, strongly transverse antennomeres VII–X ( Fig. 4a ), small eyes, long postocular area of head (at least twice length of an eye in dorsal view), short elytra (along suture shorter than length of pronotum along midline), and slightly swollen posterior part of abdomen ( Fig. 4a ), male tergite VIII truncate apically without teeth ( Fig. 4d ), and distinct shape of median lobe of aedeagus and spermatheca with narrow and moderately deep invagination of head capsule ( Figs. 4b,c,h ). The median lobe of aedeagus and spermatheca are different in shape from those of the other Nearctic Microdota species.

Description. Body narrowly subparallel, dark brown, with paler elytra and appendages ( Fig. 4a ), length 2.0–2.6 mm, integument sparsely punctate and pubescent, microsculpture of forebody distinct, sculpticells hexagonal; head broadest basally and narrowed apically, postocular region as long as two diameters of an eye; eyes small, antennomeres I–II elongate, IV moderately transverse, V–X moderately to strongly transverse, VIII–X each more than twice as wide as long ( Fig. 4a ); pronotum slightly transverse, almost subquadrate, pubescence directed laterad from midline of disc, broadest in apical third ( Fig. 4a ); elytra short, at suture shorter than pronotum along midline; abdomen slightly swollen and broadening apically, legs short ( Fig. 4a ). Male. Tergite VIII arcuate apically without teeth ( Fig. 4d )); sternite VIII parabolic apically, base slightly emarginate medially, antecostal suture arcuate ( Fig. 4e ); median lobe of aedeagus in lateral view with tubus straight basally and with narrowly triangular apex slightly projecting ventrad in lateral view, two sickle-shaped sclerites of internal sac present ( Fig. 4b ); in dorsal view median lobe as illustrated ( Fig. 4c ). Female. Tergite VIII arcuate apically ( Fig. 4f ); sternite VIII arcuate apically, antecostal suture slightly sinuate ( Fig. 4g ); spermatheca with small pear-shaped capsule with narrow and deep apical invagination; stem narrow and lengthily sinuate posteriad as illustrated ( Fig. 4h ).

Distribution. Nearctic. Canada: QC. USA: NH.

Collection and Habitat data. Specimens were found at altitudes 457–1737m, in Vaccinium , dwarf Betula , and leatherleaf litter near lake, as well as dwarf Salix , Vaccinium , and leatherleaf litter. Collected in July ( Canada) and September ( USA).

Comments. In New Hampshire this species was found in the same habitat as Borestiba parvipennis (Bernhauer) , with which it may be confused externally. Both species are of similar shape, but A. monroe is distinctly smaller/narrower and may be easily separated by its strongly transverse antennomeres VII–IX and differently shaped median lobe of the aedeagus with distinct internal sac sclerites. The external similarity of the two species is probably due to convergence caused by living in a similar habitat. This species is found only at high elevations in NH (1524–1737m) and in the Laurentian Mts. of the Gaspé Peninsula, Quebec. It is most likely widely distributed in northern Canada where it has not yet been reported.

Figures

FIGURE 4a–h. Atheta (Microdota) monroe Klimaszewski and Chandler sp. n.: (a) habitus in dorsal view; (b) median lobe of aedeagus in lateral view; (c) median lobe of aedeagus in dorsal view; (d) male tergite VIII; (e) male sternite VIII; (f) female tergite VIII; (g) female sternite VIII; (h) spermatheca. Scale bar for habitus = 1mm; remaining scale bars = 0.2mm.