Acrostilicus hospes Hubbard, 1896

Żyła, Dagmara, Tokareva, Alexandra & Koszela, Katarzyna, 2022, Phylogenetic position of genera Acrostilicus Hubbard and Pachystilicus Casey (Staphylinidae, Paederinae) and their redescription, European Journal of Taxonomy 819 (1), pp. 1-22 : 8-10

Acrostilicus hospes Hubbard, 1896

Fig. 2

Acrostilicus hospes Hubbard, 1896: 229 (original description).

Acrostilicus hospes – Blackwelder 1939: 107, 117; 1952: 37 (notes). — Moore & Legner 1979: 101. — Frania 1986: 368. — Newton et al. 2001: 387 (comment on taxonomic status). — Brunke & Buffam 2018: 154 (note on biology). — Brunke & Schnepp 2021: 888 (redescription).

Diagnosis

The species and genus can be differentiated from all other Stilicina based on the combination of the following characters: the presence of a single median tooth on the labrum, mandibles symmetrical, posterior margin of head rounded, and legs elongated.

Type material

Lectotype (designated here) USA • ♂; “ Clearwater, 27.6 Fla / CollHubbard and Schwarz / Gopher / Cotype No 22508 U.S.N.M / Acrostilicus hospes Hubbard ”; NMNH.

Paralectotypes USA • 2 ♀♀; “ Clearwater, 27.6 Fla / Coll Hubbard and Schwarz / Cotype No 22508 U.S.N.M; Funiak 4.7 Fla / Coll Hubbard and Schwarz / Cotype No 22508 U.S.N.M.”; NMNH .

Redescription

MEASUREMENTS. Medium sized (whole body length: 4.4–4.7 mm);

HABITUS. Slender, elongated, with long legs. Integument shining, with coarse, umbilicate sculpture. Head and pronotum differently punctured.

COLOURATION. Pale brown/sandy with darker head tip ( Fig. 2A ).

HEAD. Orbicular (HL: 1–1.2 mm; HW: 0.85–0.9 mm), widest in middle, wider and longer than pronotum, temples rounded and more than ½ of head length, posterior margin rounded, not emarginate, disk rugose, integument smooth and shining. Eyes large, about ¼ of head length, ½ of temple length, shifted anteriorly, slightly protruding, with setae between ommatidia. Antenna 11-segmented; antennomeres 1 and 2 with sparse pubescence; antennomeres 3 and 11 more densely pubescent, with tomentose pubescence. Antennomere 1 elongate, widest at tip; antennomeres 2–6 elongate; antennomere 7 weakly elongate; antennomeres 8–10 gradually becoming transverse; antennomere 11 elongate, 1.5 × as long as antennomere 10. Clypeal margin straight. Labrum large, transverse, twice as wide as long or wider, expanded, covering mandibles when closed, weakly sclerotised, with single short median tooth; six long, pale setae on anterior margin, evenly distributed from one edge to another, and multiple shorter setae, organised into two rows. Mandible without prostheca, with three teeth on both right and left mandible (largest one closest to base). Maxillary palpus 4-segmented; maxillary palpomere 1 short; maxillary palpomere 2 longer than wide, slightly expanded towards apex, with only few setae; maxillary palpomere 3 longer than palpomere 2 and as wide as it, slightly expanded towards apex with denser pubescence, vase-like; maxillary palpomere 4 small, acicular, glossy, and thin, equal to or shorter than width of palpomere 3. Labial palpus 3-segmented; labial palpomere 1 longer than wide; labial palpomere 2 more than twice as long as wide, wider than labial palpomere 1; labial palpomere 3 thin, much shorter and slightly narrower than labial palpomere 2. Mentum transverse, rectangular. Submentum with pair of setae on each side. Ligula entire, not bilobed, dorsal plate without setae. Gular sutures fully fused, not reaching posterior margin of head. Neck narrow, less than 1/5 of head width.

THORAX. Pronotum longer than wide (PL: 0.8 mm; PW: 0.6–0.7 mm), with anterior angles obtuse, narrowed in front, widest in middle, disc shiny, coarsely and sparsely punctured, punctures sparser than on head, evenly distributed. Basisternum of prosternum long, with longitudinal carina, prolonged behind coxa and slightly expanded laterally but not connected to hypomeron, without macrosetae or microsculpture, but surface wrinkled. Furcasternum of prosternum longer than ½ of basisternum length, triangular, acute, with sharp longitudinal carina and transversal carina. Hypomeron not delimited from pronotal disk by carina. Furcasternum of mesosternum with longitudinal carina, short, reaching ⅓ of distance between coxae, triangular. Elytra quadrate, longer and wider than pronotum (EL: 0.95–1 mm; EW: 0.85–0.9 mm), without epipleural ridge, without row of setae on edge of posterior margin and without stiff upright bristles; humeral angle indistinct, rounded; surface shiny, covered with setae not organised in distinctive rows. Scutellum without ridges, moderate, impunctate. Hind wing fully developed, MP3 vein absent, veins MP4 and CuA fused with each other. Trochantins moderate sized, oval. Coxae large, exerted. Mesocoxa contiguous, ridge below coxal rests absent. Tibiae without spines or long bristles on outer edge. Protibia with two fully developed, longitudinally placed, comb-like rows of setae, and three associated macrosetae. Tarsi 5-segmented, with one pair of empodial setae on each tarsus, equal or slightly shorter than claws (not shorter than half). Protarsus with tarsomeres 1–4 not inflated, narrower or equal to meso- and metatarsomeres, with dense pale adhesive setae on ventral side. Protarsomere 1 shorter than protarsomere 2, protarsomere 3 equal to protarsomere 2, but longer than protarsomere 4, protarsomere 4 not bilobed, protarsomere 5 longest, equal to protarsomeres 1–2 combined. Mesotarsus with mesotarsomere 1 longer than mesotarsomere 2, mesotarsomere 3 shorter than mesotarsomere 2, but longer than mesotarsomere 4, mesotarsomere 4 not bilobed, mesotarsomere 5 equal to mesotarsomere 1. Metatarsi with metatarsomere 1 twice as long as metatarsomere 2 and longer than metatarsomere 5, metatarsomeres 2–4 decreasing in length, metatarsomere 4 similar as metatarsomere 3 or shortest, metatarsomere 5 equal to 3, shorter than metatarsomeres 2–4 combined.

ABDOMEN. Finely sparsely punctate, widest at tergite V. Tergites III–VI shallowly impressed at base, with fringe of setae on posterior margin. Tergites III–VII with pair of paratergites on each side. Tergite VIII with posterior margin rounded. Sternite III without keel between coxae. Sternite VII with straight apical margin. Female: posterior margin of sternite VIII straight. Male: sternite VIII with moderately shallow and broad median emargination of posterior margin; sides of emargination on sternum VIII rounded ( Fig. 2B ). Aedeagus with parameres reduced and fused to median lobe; ventral process slightly shorter than uneverted internal sac; in parameral view with apex of ventral process rounded, sides sinuate; dorsal plate rather large and relatively weakly sclerotised ( Fig. 2C–D ).

Distribution

The species has only been recorded from Florida ( USA) ( Brunke & Schnepp 2021).

Figures

Fig. 2. Acrostilicus hospes Hubbard, 1896, habitus photograph and drawings of the apical abdominal sternite and genital structures. A. Habitus, lectotype, ♂ (NMNH). B. Male sternite VIII. C. Aedeagus, parameral view. D. Aedeagus, lateral view. Scale bar = 0.5 mm.