Phloeocharis subtilissima Mannerheim

Majka, Christopher & Klimaszewski, Jan, 2004, Phloeocharis subtilissima Mannerheim (Staphylinidae: Phloeo­ charinae) and Cephennium gallicum Ganglbauer (Scydmaenidae) new to North America: a case study in the introduction of exotic Coleoptera to the port of Halifax, with new records of other species, Zootaxa 781, pp. 1-15 : 4-6

Phloeocharis subtilissima Mannerheim

On 28 occasions between May 2001 and November 2004 the first author collected 97 specimens of P. subtilissima (CMC) in mixed coniferous woods in Point Pleasant Park. This species was not reported previously from North America ( Figures 1 and 2 ). In many living specimens the elytra appears significantly more rufous in coloration in comparison with the pronotum and abdominal segments, and is paler laterally and in the epipleural region.

Phloeocharis subtilissima appears established and abundant within the confines of Point Pleasant Park an area 75 hectares in size and mostly covered by a largely coniferous forest consisting principally of red spruce ( Picea rubens Sarg. ); white ( Pinus strobus L.), red (P. re s i n o s a Ait.), and jack ( P. banksiana Lamb. ) pine, with smaller components of balsam fir ( Abies balsamea (L.) Mill), hemlock ( Tsuga canadensis (L.) Carr.), and white spruce ( Picea glauca ). Also present is a smaller deciduous component consisting of white ( Betula papyrifera Marshall ) and wire ( Betula populifolia Marshall ) birch, red maple ( Acer rubrum L.) and red oak ( Quercus rubra L.) and various introduced species including Norway spruce ( Picea abies (L.)), scotch pine ( Pinus sylvestris L.), and European beech ( Fagus sylvatica L.) (Anonymous, 1993).

Within this forest P. subtilissima is commonly encountered primarily on limbs and trunks of recently fallen or damaged Pinus strobus , but also occasionally on Picea ruben s, P. glauca , Betula papyrifera and (once) on Amelanchier laevis Wieg. The beetle is frequently observed moving on the surface of the bark, hiding beneath bark scales, or in litter on the forest floor. It is also found in galleries excavated under the bark by scolytines, with the principal species being Crypturgus pusillus (Gyllenhal) , Hylurgops rugipennis pinifex (Fitch) , Ips grandicollis (Eichhoff) , Ips pini (Say) , Orthotomicus caelatus (Eichhoff) , and Pityogenes hopkinsi Swaine (CGMC).

Other Coleoptera commonly found in this sub­cortical environment together with P. subtilissima include Tachyta angulata Casey (Carabidae) ; Paromalus teres LeConte , Platysoma coarctatus (LeConte) , Plegaderus sayi Marseul , ( Histeridae ); Rhizophagus dimidiatus Mannerheim (Monotomidae) ; Epuraea truncatella Mannerheim (Nitidulidae) ; Silvanus bidentatus (F.) ( Silvanidae ); Charhypus picipennis (LeConte) , Homalota plana Gyllenhal , Leptusa jucunda Klimaszewski & Majka , Nudobius cephalus (Say) , Placusa tacomae Casey (Staphylinidae) ; and Corticeus praetermissus (Fall) (Tenebrionidae) (CGMC). Blue­stain ( Ophiostoma ) and other (soft­rot and white­rot) fungi are also present.

Phloeocharis subtilissima has also been found to be abundant under the bark of fallen red maple ( A. rubrum ) in a rather different environment which is bereft of scolytine galleries. Other invertebrates present in this niche include the Coleoptera Laemophloeus biguttatus (Say) (Laemophloeidae) and Phyllodrepa humerosa (Fauvel) (Staphylinidae) in addition to podurid Collembola, and juvenile millipedes (Diplopoda). In this regard it seems to be somewhat generalist in its ecological requirements.

Adult P. subtilissima were collected each month from March to December with the exception of August. Sampling during the winter months, when there was considerable snow cover and temperatures were regularly below freezing, revealed that the adults are active on sunny days when the sub­cortical environment was observed to be warmed and defrosted. Peeling away the bark revealed individuals moving around and showing no apparent signs of torpor. In this pattern of being active during the winter it is similar to the recently described sympatric species, Leptusa jucunda Klimaszewski and Majka , with which it co­occurs in Point Pleasant Park ( Klimaszewski et al. 2004). The latter species, however, is found as an adult only from mid­November to the end of April.

Thus far, P. subtilissima appears to be confined to Point Pleasant Park. Limited field investigations in Fleming Park (1.6 km from Point Pleasant Park) and at Purcell's Cove Pond (a recently designated protected area 1.2 km from Point Pleasant Park), both wooded areas with a similar composition of tree species, have not yielded specimens. It should be emphasized that there are other possible areas of suitable habitat that have not been investigated, and that the search effort in Purcell's Cove Pond and Fleming Park has been much more limited than is the case in Point Pleasant Park.

Figures

FIGURE 1: Phloeocharis subtilissima Mannerheim, Point Pleasant Park, Halifax, Nova Scotia, Canada. Dorsal habitus.

FIGURE 2: Phloeocharis subtilissima Mannerheim, Point Pleasant Park, Halifax, Nova Scotia, Canada. Living specimen in bark of red maple (Acer rubrum).