Megastilicus Casey, 1889

Żyła, Dagmara & Koszela, Katarzyna, 2021, Redescription of the genus Megastilicus Casey (Staphylinidae, Paederinae) with the description of a new species, European Journal of Taxonomy 778, pp. 138-147 : 139-141

Genus Megastilicus Casey, 1889

Figs 1–2

Megastilicus Casey, 1889: 183 (original description).

Megastilicus – Casey 1905: 227 (description and key). — Wickham 1900: 3 (note); 1911: 15 (checklist). — Leng & Wickham 1920: 24 (catalogue). — Holmquist 1928a: 84 (note); 1928b: 335 (note). — Park 1929: 199 (record/note); 1935: 217 (biology). — Blackwelder 1939: 100, 119 (key and list). — Herman 1970: 3 (note). — Moore & Legner 1979: 107–108 (description and drawing). — Newton et al. 2020: 327, 387 (key and note). — Bousquet et al. 2013: DwC-A database (checklist). — Parker 2016: 78 (note).

Type species

Megastilicus formicarius Casey, 1889 .

Diagnosis

Body robust, antennae short and stout. Body covered with short, black, stout setae. Dorsal surface of head, pronotum and elytra granulate. Head orbicular in shape.

Redescription

BODY. Medium size beetle; body robust, somewhat flattened. Colour of specimens from pale brown/sandy to brown/reddish brown. Head, pronotum and elytra covered with short, black setae. Dorsal surface of body densely granulato-reticulate, abdomen smoother, and not granulate.

HEAD. Orbicular, with rounded hind angles; widest in middle, tapering towards antennal insertions anteriorly and towards neck posteriorly; disc of head without punctation, with leather-like integument. Head wider and longer than pronotum. Antennae short, reaching only to anterior part of pronotum, compact, mostly transverse, with well-developed stems in between, pubescent. Labrum large, almost completely covering mandibles from above, notched, broadly emarginate in middle at apex, with two distinct lobes, each bearing long and pale macroseta and comb of setae near emargination; emargination bidentate; weakly sclerotised, connected with head by membrane. Mandibulae without prostheca, with two teeth on right and one on left mandibula. Maxillary palpomere 3 about twice as long as palpomere 2; palpomere 4 elongate and thin, around ⅓ of palpomere 3 length and ⅓ of palpomere 3 width. Labial palpomere 1 shorter and thinner than palpomere 2; palpomere 2 slightly elongate, expanded toward apex, twice as long as palpomere 1; palpomere 3 thin and long, longer than half of palpomere 2 and ¼ of palpomere 2 width. Mentum transverse. Submentum with pair of setae on sides. Ligula bilobed. Gular sutures fused. Eyes small, from ⅕ to ⅙ of head length. Temples long, more than half of head length. Shallow longitudinal depression on each side of head ventrally. Neck distinct and narrow, about ⅕ of head width.

THORAX. Pronotum longer than wide, anterior angles obtuse, widest in middle. Superior marginal line deflexed, becoming indistinct close to apical portion of prosternum, but reaching prosternum. Basisternum without macrosetae or microsculpture, but surface wrinkled. Furcasternum triangular, acute. Pronotal disc dull, with leather-like integument, without punctures. Elytra longer and wider than pronotum, without punctures, without epipleural ridge; humeral angles indistinct, rounded; surface dull with leather-like integument, with unorganised rows of small, black macrosetae. Anterior margin of scutellum rounded. Posterior (?) scutellar ridge present. Hind wings fully developed.

LEGS. Long and slender, uniformly covered with glossy black macrosetae. All tarsi 5-segmented. Tarsomeres 1–4 of protarsus not inflated. Protibia with three fully developed protibial combs. One pair of empodial setae on each tarsus, equal to or slightly shorter than claws (never shorter than half of claw length). Meso and metatarsomere 1 longer than 2. Metatarsi almost as long as metatibiae, with tarsomeres 1–4 decreasing gradually in length, metarsomere 1 shorter than 2 and 3 combined, slightly longer than tarsomere 5.

ABDOMEN. Sternite III with medial longitudinal keel. Abdomen widest at tergite V. Abdominal segments III to VII with pair of paratergites on each side; setae along length of abdomen. Tergite/sternite IX or X with dense setation. [Similar structure for female.]

AEDEAGUS. With parameres reduced and fused to median lobe; ventral process slightly longer than uneverted internal sac; in parameral view with apex of ventral process acute, sides sinuate; dorsal plate rather large and relatively weakly sclerotised ( Figs 1D–E , 2D–E ).

Figures

Fig. 1. Morphology of Megastilicus formicarius Casey, 1889. A. Dorsal habitus of paralectotype (NMNH). B. Dorsal habitus of lectotype (NMNH). C. Sternum VIII. D. Aedeagus in parameral view. E. Aedeagus in lateral view. Scale bars = 1 mm.

Fig. 2. Morphology of Megastilicus iowaensis sp. nov. A. Dorsal habitus of holotype (NMNH). B. Dorsal habitus of paratype (NMNH). C. Sternum VIII. D. Aedeagus in parameral view. E. Aedeagus in lateral view. Scale bars = 1 mm.