Pterostichus (Pseudoferonina) bousqueti Bergdahl

Bergdahl, James C. & Kavanaugh, David H., 2011, Two new species of Pterostichus Bonelli subgenus Pseudoferonina Ball (Coleoptera, Carabidae, Pterostichini) from the mountains of central Idaho, U. S. A., ZooKeys 104, pp. 77-96 : 78-83

Pterostichus (Pseudoferonina) bousqueti Bergdahl sp. n. Figs 13A4A, 4C56

Type locality.

U.S.A., Idaho, Boise County, small tributaries of the South Fork of the Payette River near Lowman, ca. 1200 m (3940 ft) elevation, 44.0675°; -115.6822°.

Type material.

Holotype: a male, deposited in CAS, labeled: "USA: Boise Co., Pine Flat Creek at South Fork Payette River Road, 6 km W of Lowman, 44°04'03"N; 115°40'56"W, T9N, R7E, S31, elev. 1160 m (3805 f), South Fork Payette River Basin, Boise National Forest, 05 May 1999, #26-1999, J. C. Bergdahl, coll."/ "HOLOTYPE Pterostichus bousqueti Bergdahl designated 2011" [red label]. Paratypes: A total of 11, with 8 males and 1 female with the same data as the holotype, and 2 males labeled: "USA: Boise Co., Archie Creek near confluence with SF Payette R., 8 km E of Lowman, Boise Natn. Forest, 44°04'15"N; 115°31'06"W, T9N R8E S33, elev. 1240 m (4070 ft), South Fork Payette R. watershed, 06 May 1999, #33-1999, J. C. Bergdahl, coll." The single female paratype is deposited in CAS, the male paratypes in CNC, CMNH, OSU, UICM, WSU, and JCB.

Etymology.

The specific epithet, bousqueti, is a Latinized version (genitive case) of the surname of Dr. Yves Bousquet (Agriculture Canada, Ottawa, Ontario, Canada), in recognition of his outstanding contribution ( Bousquet 1985) to our knowledge of Pseudoferonina , which brought order to the chaos in taxonomy of the species known at that time.

Diagnosis.

A Pterostichus with the characteristics of members of subgenus Pseudoferonina (see Ball 1965, and Bousquet 1999); males easily distinguished from those of all other species of Pseudoferonina by the shape of the median lobe of the aedeagus, especially the apical lamella (apex), which is shaped (in left lateral view) like the blade of a hatchet or tomahawk (Figs 4A and 4C). Also, the shaft of the median lobe in lateral view is thicker in the middle than at either end (where it joins to the base or the apical lamella) and lacks the distinct mid-shaft sinuation ( Bousquet 1985, 1992) seen in Pterostichus shulli , Pterostichus spathifer , the following new species( Pterostichus lolo ), and, to a lesser degree, Pterostichus smetanai . The small size and thin body form of Pterostichus bousqueti adults are most similar to Pterostichus campbelli adults, which occur only west of the Cascade Range in Oregon.

Description.

Size medium-small for subgenus, ABL males 8.5-9.5 mm, female 8.9 mm. Body form slightly slender for subgenus (Fig. 1).

Color. Dorsal body surface black and shiny, pronotal lateral beads piceous, legs, antennae and palpi piceous.

Microsculpture . Head with isodiametric meshes on frons; pronotum with faintly impressed transverse meshes on most of disc, meshes more isodiametric basolaterally; elytra with markedly transverse meshes, faintly iridescent in some areas.

Pronotum . Fig. 3A. Almost as long as wide, lateral margins subparallel anterior to hind angles, slightly sinuate, hind angles rectangular or slightly acute, lateral margins (in lateral view) bent ventrally near hind angles. Anterior and posterior transverse impressions present but faintly impressed, median line distinctly impressed, almost entire, but not quite extended to anterior and posterior margins in most specimens examined; anterior transverse impression faintly punctulate. Lateral margins finely beaded, posterior margin without margination, anterior margin minutely beaded in medial one-third. Basolateral fovea deep and broadly linear, slightly convergent toward midline anteriorly, not or only faintly punctulate.

Elytra.Intervals flat or only slightly convex, but less so than in any other Pseudoferonina species.

Legs. Male mesotibiae slightly curved apically.

Abdomen. Last visible sternite of male with broad, shallow medial indentation, anterior margin of depression not at all carinate, sternite without protuberances; last visible sternite of males with single pair of anal setae, female with two pairs.

Male genitalia. Median lobe of aedeagus as in Figs 4A and 4C. Apical one-third of median lobe (in ventral view) with lightly sclerotized oblique band extended longitudinally next to slight ridge (Fig. 4C); shaft of median lobe (in ventral view) swollen submedially on left, with shaft gradually tapered from swelling to the apical lamella, ventral margin not sinuate subapically (in lateral view); apical lamella average in length for Pseudoferonina species in Idaho, symmetrically hatchet-shaped (in left lateral view). Right paramere short and sharply pointed.

Geographic distribution.

At this time, Pterostichus bousqueti is known only from Pine Flat Creek and Archie Creek near their confluences with the South Fork of the Payette River near Lowman, Boise County, Idaho (Fig. 5). The Payette River is a tributary of the Snake River, which is a major tributary of the Columbia River. To what extent the range of this species is narrowly restricted to this area is not known. Despite sampling many other creeks in this area, JCB has been unable to document any other Pterostichus bousqueti populations. Additional areas, if any, in which this species is most likely to occur include the Big Pine, Deadwood, Clear Creek and Middle Fork of the Payette River watersheds to the west of Lowman and east of the North Fork of the Payette River.

Habitat.

The type locality along the South Fork of the Payette River near Lowman is in a steeply sided, sparsely pine-forested gorge (Fig. 6A) that has experienced intense forest fires. From 1908 to 2000, canopy fires burned more than 50% of the Boise National Forest in central Idaho. Large fires have a huge effect on vegetation, geomorphology, stream hydrographs ( Pierce et al. 2004), and undoubtedly Pterostichus bousqueti habitat. Fire legacies of this extent on the landscape probably create severe barriers to dispersal of Pseudoferonina species. Areas at low to mid-elevations along the South Fork of the Payette River form a small, isolated outlier of the Hot Dry Canyons eco-region of the Idaho Batholith ( McGrath et al. 2002). Most of this eco-region is associated with the main stem Salmon River, 145 km (90 miles) to the north. McGrath et al. (2002) describe this eco-region as: unglaciated, deep, precipitous canyons; annual precipitation = 305- 889 mm (lowest in deep canyons); mean temperature: Jan. (min/max) = -8.9/0.6°C, July (min/max) = 8.8/31.7°C (warmer with increasing canyon depth). The vegetation is characterized by open ponderosa pine forest and sagebrush scrub on south facing-slopes, and ponderosa pine/Douglas fir forest on north-facing slopes.

Both Pine Flat Creek (Fig. 6B) and Archie Creek are small, perennial streams descending steep canyon slopes. Their lower sections run thru dry open ponderosa pine forests. At higher elevations on sun and wind-exposed south-facing slopes, the vegetation is primarily open scrub. Pine Flat Creek descends a steep scrubby hillside; pine forest is restricted to lower reaches near the Payette River. Archie Creek descends its watersheds at a gentler grade. Both of these creeks near their confluence with Payette River are only about 1.5 m bank-full-width, and are confined primarily to channels with stabilized vegetated banks. Consequently, there are very few gravel bars on which to search for beetles, even at low water. High water for these creeks most likely occurs March-May, during rapid melt of the snow at higher elevations on adjacent hillsides coincident with wet spring storms. Because the watersheds these creeks service are so small, large thunderstorms and cloudbursts, by themselves, also may cause significant peaks in runoff during summer and fall months after the snow pack has melted at high elevation. In exceptionally dry years, both of these creeks may actually dry up to the extent that even lower sections are without surface-flowing water. However, on 25 September (2008) both creeks had nearly one meter of surface water stream width. Given their small watersheds, it is likely that major sections of both streams, especially high up where slopes are steep and the vegetation scrubby, dry up even in average years.

Other carabid species collected by JCB at or near the type locality include: forest habitat - Psydrus piceus LeConte, Pterostichus protractus LeConte; streamside habitats - Platynus brunneomarginatus (Mannerheim), Bembidion iridescens LeConte, Bembidion kuprianovi Mannerheim, Bembidion sp., Diplous aterrimus (Dejean), Nebria sp., Bradycellus californicus (LeConte), Bradycellus nigrinus (Dejean), Bradycellus nubifer LeConte. The trout-stream beetle Amphizoa insolens LeConte (Coleoptera, Amphizoidae) also occurs along creeks in this area.

Phenology and larval ecology.

JCB visited Pine Flat Creek and Archie Creek on two occasions: 05-06 May (1999) and 25 September (2008). In early May, he easily found adults of Pterostichus bousqueti at both sites, however in September collecting along these same stream sections on both creeks yielded no specimens. Pseudoferonina populations in hot dry regions at low elevations appear to aestivate or go into early hibernation, probably in August. Very few teneral specimens have been collected; however, males with soft, poorly chitinized median lobes are common in late summer and fall. This suggests that adults emerge from pupal chambers in late summer through early fall and overwinter as adults. Presumably they escape winter-spring floods by migrating out of the floodplain to higher positions along stream banks to hibernate in the fall before freeze-up, however they probably do not go very far. Once snow packs melt and daytime temperatures approach 10°C (late March and early April at lower elevations in Idaho), adults again become active on the surface. Given the fact that surface-active Pseudoferonina adults are so closely associated with the immediate vicinity of stream margins, the larvae are probably also narrowly restricted to these habitats and may spend a substantial amount of time subsurface at or very near the hyporheic zone.

Dispersal power.

All known individuals are brachypterous (flightless) and restricted to the margins of small, isolated, forested streams, so dispersal power of Pterostichus bousqueti adults is expected to be extremely low. Like Pterostichus shulli , Pterostichus spathifer and Pterostichus lolo sp. n., the geographic range of Pterostichus bousqueti (Fig. 5) appears to be highly restricted.

Remarks.

Among Idaho’s Pseudoferonina species, Pterostichus bousqueti appears to be a member of the lanei species-group (with Pterostichus lanei ), as opposed to the shulli species-group ( Pterostichus shulli , Pterostichus spathifer and Pterostichus lolo sp. n.). Idaho species in the shulli group have a distinct ventral sinuation (bulge and concavity) on the ventral surface of the median lobe of the aedeagus near the middle of the shaft (easily seen in lateral view). Species in the lanei group (and Pterostichus vexatus ) do not have this feature. To what extent this feature, or its absence, is indicative of phylogenetic relationship is presently unknown.

Property ownership in the South Fork Payette River area in vicinity of the type locality is primarily the U.S. Forest Service (Boise National Forest), however according to the Boise National Forest map there are many small in-holdings along the river. Two of these in-holdings include both lower Pine Flat and lower Archie creeks, near where the type specimens were collected. Both of these creeks probably have experienced prospecting or mining activity. There is a small Forest Service campground and hot springs very near Pine Flat Creek on the north bank of the Payette River, but visitors seem to have little impact on the creek.

Because Pterostichus bousqueti is known from only two easily identifiable localities, we hope that collectors will exercise restraint when sampling at these sites, and instead focus on discovering new sites for this species in the immediate vicinity, such as in those watersheds listed above.