Isoglossa triangularis Klimaszewski, Brunke & Pentinsaari, 2021

Brunke, Adam J., Pentinsaari, Mikko & Klimaszewski, Jan, 2021, Integrative taxonomy of Nearctic and Palaearctic Aleocharinae: new species, synonymies, and records (Coleoptera, Staphylinidae), ZooKeys 1041, pp. 27-99 : 27

Isoglossa triangularis Klimaszewski, Brunke & Pentinsaari sp. nov. Fig. 5A-H

Type material.

Holotype. (male): Canada, British Columbia, Prince George, Nukko Lake Elementary EQP-CLL-574, 54.0831°N, 122.988°W, 764 m asl, Holly Sapun 04/20/2015 to 05/08/2015, Barcode of life, DNA voucher specimen, Sample ID: BIOUG22036-B02, Process ID: SMTPM2682-15 (CNC). Paratypes (3, CBG): Canada, British Columbia, Prince George, Nukko Lake Elementary EQP-CLL-574, 54.0831°N, 122.988°W, 764 m asl, Holly Sapun 04/20/2015 to 05/08/2015, Barcode of life, DNA voucher specimen, Sample ID: BIOUG22036-B07, Process ID: SMTPM2682-15 (1 male, CBG); same label data except: Sample ID: BIOUG22035-H08, Process ID: SMTPM2665-15 (1 female, CBG); Sample ID: BIOUG22036-A04, Process ID: SMTPM2672-15 (1 female, CBG).

Etymology.

The species epithet refers to the remarkably separated triangular apex of the median lobe of the aedeagus, distinguishing it from all other members of the Ocalea group.

Distribution.

Origin: Nearctic. Canada: BC.

Diagnosis.

Isoglossa triangularis can be easily distinguished from all Nearctic species of the Ocalea group of genera by a combination of the strongly transverse and sparsely punctate pronotum, transverse antennomere 4, distinct triangular apex of the median lobe in lateral view (Fig. 5B ), and distinct and simple 'walking cane’ shape of the spermatheca (Fig. 5D ).

Description.

Body length 3.0-3.3 mm, dark brown with elytra, antennomeres 1-2 or 1-3, legs and apical part of abdomen yellow-brown, forebody moderately glossy and abdomen strongly so (Fig. 5A ); antenna moderately stout, antennomere 4 slightly transverse, antennomeres 5-10 strongly transverse, terminal antennomere ca. as long as two preceding ones combined; pronotum transverse (width/length ratio = 1.6), impressed medially at base, lateral edges evenly arcuate, length ratio of base to apex 1.2 ×, punctures fine and sparse, distance between punctures ~ 3 × diameter of a puncture, space between punctures with faint isodiametric microsculpture, pubescence directed laterad from midline of disc forming arcuate lines on both sides; elytra transverse (width/length ratio = 1.3), 1.5 × as long as pronotum; abdomen arcuate laterally and gradually narrowing toward apex. MALE. Tergite VIII broadly arcuate apically (Fig. 5E ); sternite VIII with apical part broadly triangularly produced (Fig. 5F ); median lobe of aedeagus in lateral view with narrowly elongate crista apicalis at base of bulbus, tubus moderately long, strongly produced ventrally, apex narrowly triangular constricted baso-dorsally in lateral view (Fig. 5B ), internal sac structures not pronounced (Fig. 5B, C ). FEMALE. Tergite VIII truncate apico-medially (Fig. 5G ); sternite VIII arcuate apically (Fig. 5H ); spermatheca with capsule approximately spherical with short neck, stem narrow, long and straight (Fig. 5D ).

Bionomics.

The specimens were collected in a Malaise trap on an open field surrounded by mixed forest.

Comments.

Based on a combination of small size (<4.5 mm), superficial, meshed microsculpture, sparse pronotal punctation, with punctures separated by more than two puncture diameters, pronotum transverse, shorter and narrower than elytra, and the transverse antennomeres 5-10, I. triangularis keys to genus Isoglossa Casey in Klimaszewski and Pelletier (2004). However, barcode sequences of this species do not cluster with Isoglossa agnita but rather form a cluster with Gennadota canadensis and the species of Neothetalia which bear a spermatheca with broad, circular loops, similar to those of Gennadota . Isoglossa triangularis has a simple spermatheca with a long straight stem and is not externally similar to these taxa (see above), and the barcode divergence between these species and I. triangularis is 11-12%. It is likely that I. triangularis belongs in a separate genus, but this is outside of the scope of this study. We here place I. triangularis tentatively in Isoglossa as not to disturb the existing morphological diagnoses of the genera and identification keys (e.g., Klimaszewski and Pelletier 2004; Klimaszewski et al. 2020), pending generic revision of the Ocalea group.

Figures

Figure 5. Isoglossa triangularis Klimaszewski, Brunke & Pentinsaari, sp. nov. A habitus B median lobe of aedeagus in lateral view C median lobe of aedeagus in dorsal view D spermatheca E male tergite VIII F male sternite VIII G female tergite VIII H female sternite VIII. Scale bars: 1 mm (A); 0.2 mm (B-H).