Hydrosmecta caduca Casey, 2000

Klimaszewski, Jan, Webster, Reginald P. & Davies, Anthony, 2017, Genus Hydrosmecta C. G. Thomson: a review of species occurring in eastern Canada (Coleoptera, Staphylinidae, Aleocharinae), Insecta Mundi 2017 (593), pp. 1-17 : 5-6

Hydrosmecta caduca Casey

( Fig. 9–16 )

Hydrosmecta caduca Casey 1910: 87 .

Lectotype (male): New York [Catskill Mts. in original description]; caduca Csy. [Casey]; Type USNM 39085 ; Casey bequest 1925 ; Lectotypus: Hydrosmecta caduca Casey, V.I. Gusarov 2000 (USNM) male, with aedeagus missing. Present designation.

New Canadian records: Canada, New Brunswick: Queens Co., Bayard, at Nerepis River , 45.4426°N, 66.3280°W, 25. V.2008, R. P. Webster // river margin, under small rocks in gravel ( LFC) 2 males, 3 females ( NBM) 1 male ( RWC) 1 male, 1 female ; Bayard, at Nerepis River , 45.4426°N, 66.3280°W, 30. V.2008, R. P. Webster // river margin, under small rocks in gravel ( LFC) 1 female ( RWC) 1 male ; Bayard, at Nerepis River , 45.4426°N, 66.3280°W, 7. VI.2017, R. P. Webster // river margin, in gravel near water ( NBM) 1 female ; Canning, Grand Lake, Goat Island , 46.0110°N, 66.0133°W, 8. VIII.2007, R. P. Webster // Lakeshore, on cobblestone beach, under cobblestone in moist sand ( LFC) 1 male ; Restigouche Co., Jacquet River Gorge , 47.8257°N, 66.0779°W, 14. V.2010, R. P. Webster // partially shaded cobblestone bar near outflow of brook, cobblestones and gravel on sand ( LFC) 1 male, 2 females ( RWC) 2 males ; Carleton Co., Belleville, Meduxnekeag Nature Preserve , 46.1942°N, 67.6832°W, 9. VI.2008, R. P. Webster // river margin, among small cobblestones set in sand and fine gravel near water’s edge ( LFC) 1 male ( RWC) 3 females ; Belleville, Meduxnekeag Nature Preserve , 46.1942°N, 67.6832°W, 11. VI.2008, R. P. Webster //river margin, under cobblestones set in sand with grass roots ( LFC) 1 male .

Diagnosis. Body length 1.9–2.0 mm; subparallel, flattened, light brown with head and abdomen dark brown, legs and basal antennomeres yellow; moderately glossy, with fine and dense punctation and pubescence; faint meshed microsculpture present on forebody ( Fig. 9 ); head as wide as pronotum, postocular area about as long as diameter of eye, posterior angles rounded; eyes moderately large; antennae long, reaching posterior margin of elytra, all antennomeres distinctly elongate, antennomere XI about as long as two preceding antennomeres combined; pronotum subquadrate, widest in apical third, as wide as head and abdomen but narrower than elytra, slightly depressed medially; elytra elongate and flattened, at suture slightly longer than pronotum; abdomen subparallel, slightly narrowed apically. Male: apical margin of tergite VIII sinuate, medially broadly shallowly emarginate ( Fig. 12 ); sternite VIII longer than wide, broadly arcuate apically, distance between antecostal suture and basal margin wide ( Fig. 13 ); median lobe of aedeagus in lateral view with large bulbus, tubus triangular, with venter sinuate and with small, narrow basal projection narrowly separated from venter of tubus ( Fig. 10 ); in dorsal view tubus constricted medially ( Fig. 11 ). Female: tergite VIII similar to that of male ( Fig. 14 ); apical margin of sternite VIII truncate medially, broadly rounded laterally apically and slightly concave medially ( Fig. 15 ); spermatheca with capsule short with moderate-sized apical invagination, stem sinuate and broadly looped posteriorly, with base slightly swollen ( Fig. 16 ).

This species is very similar to H. canadensis , from which it may be distinguished by shorter and narrower body, less elongate apical antennomeres, basal projection of bulbus longer and narrowly separated from tubus in lateral view ( Fig. 10 ), tubus distinctly constricted at middle in dorsal view ( Fig. 11 ), and spermathecal coils slightly tighter ( Fig. 16 ).

Distribution. Origin: Nearctic. Canada: NB. USA: NY.

Collection and habitat data. Habitat: This is a riparian species associated with gravel and sand near river margins ( Fig. 48 ), but it was also reported from a lakeshore. Specimens were collected from under small rocks in gravel along a river margin, from under small cobblestones set in sand and fine gravel near water edge along a river margin, and from a partially shaded cobblestone bar near outflow of a brook. Most specimens were found close to the river margin. One individual was found among grass roots under a cobblestone set in sand along a river margin; another from under a cobblestone set in sand on a cobblestone beach on a lakeshore. Collecting period: V, VI, VIII. Collecting method: turning gravel and cobblestones and aspirating specimens.

Comments. This is the first record of this species from Canada and NB. We have compared the lecto- type male with our specimens and they agree with the lectotype in shape of tergite and sternite VIII and external characters, including its size, shape, proportions of antennomeres, color and pubescence pattern. The lectotype male is missing the median lobe of the aedeagus. Because Gusarov’s designation was never published, we formally designate this specimen as the lectotype with our designation label. The male and female of this species are redescribed and illustrated for the first time, including habitus, tergite and sternite VIII, median lobe of aedeagus and spermatheca.

Figures

Figure 48. Gravel bar habitat at Nerepis River, Queens Co., Bayard, NB, habitat for Hydrosmecta caduca Casey, H. canadensis Webster and Klimaszewski, sp. nov. (type locality),H. dulcis Casey, andH. minutissimoides Webster and Klimaszewski, sp. nov. (type locality).

Figures 9–16. Hydrosmecta caduca Casey. 9) Habitus in dorsal view.10) Median lobe of aedeagus in lateral view. 11) Median lobe of aedeagus in dorsal view. 12) Male tergite VIII. 13) Male sternite VIII. 14) Female tergite VIII. 15) Female sternite VIII. 16) Spermatheca. Scale line for habitus = 1 mm, remaining scale bars = 0.2 mm.