Anillinus choestoea Harden & Caterino, 2024, sp. nov.

Anillinus choestoea sp. nov. Figs 10 E, 11 B, D, 12 C, 21 J, 24 I, 34 C, 35 A – C, 36 Type material. Holotype male (USNM) : point mounted, with abdominal ventrites glued to point and genitalia in Euparal on microslide pinned beneath specimen. Original label: “ USA: SOUTH CAROLINA, Oconee Co. Choestoea Park. 34.54616, - 83.10479. 21. December. 2020. CW Harden. Under small rocks, pine / oak hill. Soft, moist sandy soil. ” “ [QR code] CLEMSON-ENT CUAC 000163546 ” “ Harden DNA Voucher CWH- 335 A. ‘ choestoea ’ M Ext. 1 / May / 2021 [green-bordered cardstock] ” “ HOLOTYPE Anillinus choestoea Harden & Caterino [orange cardstock] ” GenBank: OR 839239, OR 839627, OR 838052. Paratypes (n = 4, CUAC). USA • South Carolina • 2 ♀; same data as holotype; CUAC 000163544 and CUAC 000163545, CWH- 336 and CWH- 337; • 1 ♂; Oconee Co.; Choestoea Park; 34.54318, - 83.09894; 21 Dec. 2020; C. W. Harden leg.; Under rock in Camponotus nest; CUAC 000163543, CWH- 310; • 1 ♀; Oconee Co.; Choestoea Park; 34.5477, - 83.1052; 19 Feb. 2022; C. W. Harden leg.; Under rock; CUAC 000163547. GenBank accession numbers for paratypes: OR 853202, OR 839240, OR 839608, OR 837897, OR 838043, OR 838232, OR 839628, OR 839629. Diagnosis. Compared to other members of the sinuaticollis group, the habitus of this species is broader (EW / ABL 0.37 or 0.38) and more convex (Fig. 34 C). The microsculpture on the pronotum is more extensive, present anteriorly and extending onto the disc in some specimens. The aedeagus is also unique (Fig. 35 C), most notably the dorsally expanded apex of the median lobe and the short, dorsally rotated flagellum of the internal sac. Description. Habitus (Fig. 34 C) ABL = 1.61–1.81 mm, males (1.81 mm) larger than females (1.61–1.65 mm), slightly convex and ovoid (EW / ABL = 0.37–0.38). Integument Irregular isodiametric microsculpture present anteriorly on pronotum, becoming effaced posteriorly and indistinguishable from surface rugosity, which is strong; microsculpture present across entire dorsal surface of head. Dorsal microsculpture is stronger in males than in females. Head HW / PW = 0.74–0.78. Antennomeres IV – X moniliform. Labrum shallowly emarginate anteriorly. Frontoclypeal horn present, well developed. Three pairs of supraorbital setae present, outer posterior pair shorter than other two. Mentum with median pair of setae posterior to bead of mentum tooth, which is small and subtriangular. Pronotum Strongly constricted basally in females (Pbw / PW = 0.73–0.74), less so in males (Pbw / PW = 0.78); short in both sexes (PL / ABL = 0.22–0.24). Moderately broad (average PW / EW = 0.81). Sides straight or slightly sinuate before obtuse hind angles; 2–4 basal serrulations. Elytra Moderately to markedly ovoid, more so in females than in males; moderately convex; relatively long (EL / ABL = 0.55–0.57); humeri not sloped; inner two striae well impressed, traces of two or three additional striae visible. Legs Protarsi of males with protarsomere 1 expanded and spinose on inner margin, with adhesive setae ventrally, protarsomere 2 unmodified and without adhesive setae (Fig. 10 E). Metafemora of males (Fig. 12 C) not strongly swollen, without prominent tubercle or tooth on posterior margin. Abdominal ventrites Unmodified in either sex. Male genitalia Aedeagus relatively small (RL / ABL = 0.24). Median lobe (Fig. 35 C) not twisted, evenly curved; dorsal margin sclerotized for ~ 1 / 2 its length; ventral margin without setae; apex large and broadly rounded, produced dorsally into lightly sclerotized lobe subequal to apex in size and shape; internal sac with flagellum rotated dorsally so that it is viewed through base in right lateral view and appears as a complex sclerotized structure; in dorsal view, flagellum is short and evenly curved, broadly “ open ” laterally, not closed at apex, with elongate basal extension; rows of lightly sclerotized teeth present along left side of internal sac beside flagellum and ostium; texture of internal sac slightly scaly at ostial opening. Right paramere (Fig. 35 B) lightly sclerotized and quadrate, apical margin blunt and enlarged, with four moderately long setae basally. Left paramere (Fig. 35 A) subtriangular, with four pores along lower margin near apex, without setae. Female genitalia Spermatheca long, gradually enlarged distally, stem coiled proximally (Fig. 21 J); duct damaged in all specimens examined. Distribution. Known from a small area of Choestoea Park in Oconee Co., SC, located along the former course of the Tugaloo River, currently inundated by Lake Hartwell (Fig. 36). Sympatry. This species has not been collected in association with other anilline species. Species status justification. The genitalic morphology of males and females of this species is unique within the genus. DNA sequence data indicate that A. choestoea is most closely related to geographically distant members of the sinuaticollis group, all of which differ from A. choestoea in external structure and male genitalic characters. Natural history. Known from endogean microhabitats. One specimen was collected in the galleries of Camponotus ants under a large rock. The remaining specimens were collected underneath smaller rocks embedded in sandy clay rich soil without evidence of Camponotus galleries. It is unlikely that the species is closely associated with ant hosts. Specimens were collected in December and February. Derivation of species name. From the type locality, Choestoea Park, to be treated as a noun in apposition. Notes. Anillinus choestoea belongs to a subclade that is otherwise comprised of western species. All share a similar flagellum shape that is short and rotated dorsally so that in lateral aspect it is viewed through the base.