Amarochara formicina, Assing, Volker, 2007

Assing, Volker, 2007, A revision of Amarochara of the Holarctic region. III. A new species, a new synonym, and additional records (Coleoptera, Staphylinidae: Aleocharinae), Zootaxa 1411, pp. 25-32 : 26-29

Amarochara formicina sp. n.

( Figs. 1–14 , 20 )

Type material. Holotype ɗ: Can[ada]., New Brunswick, York Co., New Maryland Charters Settlement, 45.8275°N, 66.7368°W, 30 April 2005, R. P. Webster, coll. / Red spruce/cedar forest, In nest of black Formica , sifting nest material / Holotypus ɗ Amarochara formicina sp. n. det. V. Assing 2006 (LFC). Paratypes: 2ɗɗ: same data as holotype (LFC, cAss).

Description. Body length 3.5–4.1 mm; habitus as in Fig. 1 . Coloration: head dark brown to blackish brown; pronotum brown to blackish brown, of similar coloration as head or paler; elytra brown to dark brown, slightly paler than pronotum ( Fig. 20 ); abdomen reddish brown, with posterior margins of tergites III–VI, posterior 1/2–1/3 of tergite VII, and segments VIII–X reddish yellow; legs yellowish brown; antennae dark brown, with antennomeres I–II/III and XI slightly paler.

Head posteriorly without distinct neck, approximately as wide as long and of subquadrate shape, lateral margins subparallel in dorsal view; microsculpture conspicuously coarse, surface almost completely matt, only frons with small areas with slightly less pronounced microsculpture and subdued shine ( Figs. 2 , 20 ); puncturation fine, indistinguishable from microsculpture; eyes moderately large, slightly shorter than postocular region in dorsal view; genal carina very fine ( Fig. 3 ). Maxillary palpus slender, preapical palpomere more than 3 times as long as wide. Antennae stout and relatively short; antennomere I approximately 1.5 times as long as wide and with pronounced dorso-apical furrow; II approximately as long as I; III somewhat shorter than II, coniform, and approximately 1.5 times as long as wide; IV almost twice as wide as long; V–X of increasing width and increasingly transverse, X at least 3 times as wide as long; XI of ovoid shape and slightly longer than the combined length of IX–X ( Fig. 4 ).

Pronotum approximately 1.15 times as wide as long and 1.3 times as wide as head, maximal width near the moderately marked posterior angles; microsculpture as coarse as or even more pronounced than that of head, but surface slightly more shiny; puncturation not discernible in microsculpture; pubescence pale and depressed, denser and more distinct than that of head ( Figs. 2 , 20 ).

Elytra approximately 1.25 times as wide and at suture 0.8 times as long as pronotum; posterior margin very shallowly sinuate near posterior angles; puncturation dense, moderately fine, and ill-defined; microsculpture shallow, much less pronounced than that of head and pronotum ( Figs. 2 , 20 ); mesosternum without median carina; mesosternal process long and apically acute, reaching more than halfway between mesocoxae. Metatarsomere I longer than the combined length of II–III, but shorter than the combined length of II–IV.

Abdominal tergites III–V with moderately deep, densely punctured, but not carinate anterior impressions, remainder of these tergites with less dense and more well-defined puncturation; puncturation of posterior tergites much sparser than that of anterior tergites; microsculpture present, but shallow ( Fig. 5 ); tergite X anteriorly not distinctly elongated and rather broad.

ɗ: tergite VIII posteriorly truncate ( Fig. 6 ); posterior margin of sternite VIII truncate and with dense long marginal setae ( Fig. 7 ); median lobe of aedeagus with ventral process approximately as long as basal capsule and laterally carinate; ventral process apically shallowly incised; internal sac with rather long flagellum ( Figs. 8–12 ); paramere with small apical lobe ( Figs. 13–14 ).

&: unknown.

Comparative notes. The species is readily distinguished from other congeners occurring in the Holarctic region by the morphology of the aedeagus and by the conspicuously coarse microsculpture of the head and pronotum. Based on the morphology of the aedeagus (shape of median lobe with basally carinate ventral process; internal sac with long flagellum, semi-transparent plate-like apical structures; shape and chaetotaxy of paramere), as well as on external characters (morphology of antenna, body proportions, morphology of mesosternum), and also the similar ecology (presumed association with ants of the genus Formica ), A. formicina is a close relative, probably the sister species of A. inquilina . From the latter, the new species is readily distinguished by the much coarser microsculpture of the head and pronotum, distinctly larger size, the stouter and apically more distinctly incrassate antennae, the shape of the pronotum (in A. inquilina maximal width approximately in the middle), the much more distinct microsculpture and puncturation of the elytra and the abdomen, as well as by the distinctly larger and differently shaped aedeagus.

In order to account for the new species, the key in Assing (2002a) is modified as follows:

12. E-Palaearctic species.................................................................................................................................. 13 - Nearctic species ........................................................................................................................................16a [...]

16a. Head and pronotum with conspicuously coarse microsculpture, almost completely matt ( Figs. 2 , 20 ). ɗ: median lobe of aedeagus as in Figs. 8–12 . E-Canada: New Brunswick. .................................. A. formicina - Head and pronotum without or with very shallow microsculpture, shiny. Male sexual characters different. ................................................................................................................................................................... 17

Etymology. The name (Latin, adjective: relating to ants) refers to the fact that this species was found associated with ants.

Distribution and bionomics. The species is known only from one locality in New Brunswick, eastern Canada, where it was discovered in a spruce and cedar forest in a nest of Formica cf. fusca Linné. The identification of the ant workers, which were mounted together with the types, is based on the key by Creighton (1950) and a comparison with material from Central Europe.

Figures

FIGURES 1 – 7. Amarochara formicina sp. n. 1 — habitus; 2 — forebody; 3 — head in lateral view; 4 — antenna; 5 — abdomen; 6 — male tergite VIII; 7 — male sternite VIII. Scale bars: 1: 1.0 mm; 2 – 7: 0.5 mm.

FIGURES 8 – 14. Amarochara formicina sp. n. 8 – 11 — median lobe of aedeagus in lateral and in ventral view; 12 — apical part of median lobe of aedeagus in ventral view; 13 — paramere; 14 — apical lobe of paramere. Scale bars: 8 – 13: 0.2 mm; 14: 0.1 mm.

FIGURES 19 – 21. Habitus and forebody of Amarochara species. 19 — habitus of A. freyi (Bernhauer) (holotype); 20 — forebody of A. formicina sp. n.; 21 — forebody of A. inquilina (Casey). Scale bars: 20 – 21: 1.0 mm; 19 without scale.