Acrostilicus hospes Hubbard, 1896

Brunke, Adam J. & Schnepp, Kyle E., 2021, Taxonomic Changes in Nearctic Paederinae, New Records and a Redescription of the Enigmatic Genus Acrostilicus Hubbard (Coleoptera: Staphylinidae), The Coleopterists Bulletin 75 (4), pp. 883-894 : 888

Acrostilicus hospes Hubbard, 1896 ( Figs. 1A–F , 2A–F )

Acrostilicus hospes Hubbard 1896: 299 .

Type Material. Syntypes (1 male, 2 females, NMNH): “[specimen head, prothorax, meso/metatho- rax, basal abdomen each glued to thin point]/ Clearwater, 27.6 Fla [typed label] /Coll Hubbard & Schwarz [typed label]/Gopher [handwritten]/Cotype No 22508 U.S. N.M [red printed label]/ Acrostilicus hospes Hubbard [handwritten]” [1 male] .

Labels as above, [body intact, 1 female]. Labels as above, except “4.7 Fla” [body intact, 1 female].

Note on Type Material. Specimens are in mod- erate to poor condition and the male has been previously disarticulated. We have not designated a lectotype because the identity of this distinctive taxon is not in question.

Other Material. UNITED STATES: Florida: Hamilton Co., 12 miles E Madison, 30.48852, −83.21186, 17–20.IX.2017, black cup pitfall, Kyle E. Schnepp (2, KESC) .

Diagnosis. Easily recognized as the only species of the genus.

Redescription. Forebody 2.6–2.8 mm. Coloration: pale yellowish-brown, with legs and elytra slightly paler, yellowish ( Fig. 1A ).

Head approximately as long as wide (1.035 l/w); punctation moderately dense, coarse and umbilicate, interstices narrow, most punctures clearly but narrowly separated by a distance less than 1/4 of their diameter, punctures more widely separated in center of disc and on frons. Eyes bulging, temples about 1.6 times as long as eyes. Antenna long, about as long as head and pronotum combined, antennomeres 1–7 elongate, 8–10 subquadrate to slightly transverse. Pronotum elongate-hexagonal, sides weakly explanate, distinctly narrower and shorter than head; disc with relatively broad median impunctate line, about 3–4 puncture diameters wide, sometimes narrowing to 2 puncture diameters wide, punctures much finer than on head, simple and sparser, most separated by more than 1 puncture diameter; elytra longer and much broader than pronotum; punctation finer than that of head, simple, punctures separated by more than their diameter, interspaces with irreg- ularly spaced micropunctures; scutellar shield sparsely punctate; wings fully developed. Metatarsomere I longer than II and III combined. Abdomen about as wide as elytra, punctation fine, moderately dense; distinct microsculpture absent; posterior margin of tergite VII with palisade fringe. Male with sternites as described for the genus; aedeagus with ventral process shorter than uneverted internal sac; aedeagus in ventral view with apex of ventral process acute but rounded, sides slightly sinuate ( Fig. 2D ); aedeagus in lateral view with ventral process strongly produced ventrad, dorsal face of process with apical and subapical teeth ( Fig. 2E ).

Distribution. This species is currently known only from Hamilton and Pinellas counties in Florida but may co-occur broadly in the southeast with the gopher tortoise ( Gopherus polyphemus (Daudin) ; Testudines: Testudinidae ) in suitable habitats.

Bionomics. Both adults and larvae of this species have been directly collected from burrows of the gopher tortoise ( Hubbard 1896). To our knowledge, no records have been published since. More than 100 years later, one of us (KES) collected two specimens of this species from black pitfall traps, which tend to capture burrow-associated Coleoptera . Additional species associated with gopher tortoises that were collected from the same black-cup pitfalls include Philonthus gopheri Hubbard ( Coleoptera : Staphylinidae ) and Alloblackburneus troglodytes (Hubbard) ( Coleoptera : Scarabaeidae ).

Figures

Fig. 1. Acrostilicus hospes. A) Dorsal habitus, B) Labrum in dorsal view, showing median tooth (arrow), C) Labrum in ventral view, showing marginal row of setae (arrow), D) Head in ventral view, E) Head in ventral view, anterior close-up, F) Anterior disc of head, dorsal view, showing umbilicate punctures. G = galea; LP = labial palpus. Scale bars = 1 mm (A), 0.2 mm (B–F).

Fig. 2. Acrostilicus hospes. A) Left mandible, ventral view, B) Prosternum, C) Protibia, showing ctenidia, D) Aedeagus, ventral view, E) Aedeagus, lateral view, F) Male sternite VIII (upper) and male sternite IX (lower), setae and male tergite X omitted for clarity. VP = ventral process; LP = lateral plates of the internal sac; DP = dorsal plate of the internal sac; LS = lateral struts. Scale bars = 0.2 mm.