Pleuroseta ingens Kuwahara & Marshall 2023, sp. nov.
Creators: name: Kuwahara, Gregory K.
name: Marshall, Stephen A.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Sphaeroceridae
Pleuroseta
Pleuroseta ingens

description: Pleuroseta ingens sp. nov.
urn:lsid:zoobank.org:act: 1DA3EC33-1534-4015-8550-AC654579CB56
Figs 1, 5D, 6–9, 16A
Etymology
The species name (from the Latin ingens’,’huge, ‘enormous’) refers to the greatly enlarged male genitalia and the very large, cup-shaped female epiproct.
Material examined
Holotype
AUSTRALIA • ♂; Queensland, Bartle Frere; 17°23' S, 145°48' E; 1000 m a.s.l.; 29–30 Nov. 1998; G.B. Monteith leg.; boulder cave, dung trap; QMBA debu00160983.
Paratypes
AUSTRALIA – Queensland • 2 ♂♂, 2 ♀♀; same collection data as for holotype; DEBU • 3 ♂♂, 2 ♀♀; same collection data as for holotype; QMBA • 1 ♂, 1 ♀; 7 km NE of Ravenshoe; 17°34' S, 145°31' E; 1080 m a.s.l.; 3–5 Feb. 1999; G.B. Monteith leg.; rainforest, dung pitfall; DEBU • 2 ♀♀; 9.5 km N of Ravenshoe; 17°32' S, 145°29' E; 1060 m a.s.l.; 14–17 Apr. 1999; G.B. and S.R. Monteith leg.; wet sclerophyll, dung trap; QMBA • 1 ♀; Arthur Baillie Road; 17°41' S, 145°31' E; 1000 m a.s.l.; 6–8 Feb. 1999; D.J. Cook leg.; rainforest, automatic dung trap (night); QMBA • 2 ♂♂, 2 ♀♀; Bellenden Ker, top station; 17°16' S, 145°51' E; 1500 m a.s.l.; 30 Nov.–2 Dec. 1998; Monteith and Cook leg.; automatic dung trap, 5:30 am –6:15 pm; QMBA • 3 ♂♂, 3 ♀♀; Bellenden Ker, top station; 17°16' S, 145°51' E; 1500 m a.s.l.; 30 Nov.–2 Dec. 1998; G.B. Monteith leg.; dung traps; DEBU • 1 ♂, 2 ♀♀; Charmillin Creek; 17°42' S, 145°31' E; 900 m a.s.l.; 2–5 Dec. 1998; Monteith and Cook leg.; automatic dung trap, 5:30 am –6:15 pm; QMBA • 1 ♂, 4 ♀♀; Kjellberg Road, State Forest boundary; 17°32' S, 145°35' E; 920 m a.s.l.; 6–9 Feb. 1999; G.B. Monteith leg.; rainforest, dung pitfall; DEBU • 1 ♀; Kjellberg Road turnoff; 17°32' S, 145°36' E; 740 m a.s.l.; 6–9 Feb. 1999; G.B. Monteith leg.; rainforest, dung pitfall; DEBU • 5 ♂♂, 6 ♀♀; Longlands Gap, three-ways Road junction; 17°28' S, 145°29' E; 1060 m a.s.l.; 3–6 Feb. 1999; Monteith and Cook leg.; wet sclerophyll, dung trap; QMBA • 1 ♀; same collection data as for preceding; rotten bait; DEBU • 1 ♂; Maalan State Forest, Ravenshoe Road; 17°35' S, 145°36' E; 840 m a.s.l.; 6–9 Feb. 1999; D.J. Cook leg.; rainforest, dung pitfall; DEBU • 7 ♂♂, 2 ♀♀; Millaa Millaa Falls; 17°30' S, 145°51' E; 800 m a.s.l.; 6–9 Feb. 1999; G.B. Monteith leg.; rainforest, dung pitfall; QMBA • 2 ♂♂, 9 ♀♀; Mount Hugh Nelson, south base; 17°31' S, 145°33' E; 1080 m a.s.l.; 7–9 Feb. 1999; Monteith and Cook leg.; rainforest, dung pitfall; QMBA • 5 ♂♂, 6 ♀♀; same collection data as for preceding; rotten bait; DEBU • 2 ♂♂; Mount Hypipamee National Park; 11–17 Apr. 1999; S.A. Marshall leg.; dung; DEBU • 5 ♂♂, 1 ♀; Mount Kooroomool, 7 km south of the summit; 17°54' S, 145°41' E; 1050 m a.s.l.; 3–4 Dec. 1998; G.B. Monteith leg.; dung trap (night/dawn); QMBA • 3 ♂♂, 6 ♀♀; same collection data as for preceding; 4 Dec. 1998; dung trap (day); DEBU • 3 ♂♂, 5 ♀♀; same collection data as for preceding; dung trap (dusk); QMBA • 4 ♂♂, 3 ♀♀; The Millstream, 10 km NNE of Ravenshoe; 17°32' S, 145°31' E; 1040 m a.s.l.; 3–5 Feb. 1999; Monteith and Cook leg.; rainforest, dung trap; DEBU • 5 ♂♂, 4 ♀♀; same collection data as for preceding; QMBA • 7 ♂♂, 6 ♀♀; Vine Creek, Majors Mountain; 17°41' S, 145°32' E; 1060 m a.s.l.; 4–6 Feb. 1999; Monteith and Cook leg.; rainforest, dung pitfall; DEBU • 1 ♀; same collection data as for preceding; fish pitfall; DEBU.
Description
BODY (Fig. 6A). Length 2.8–4.4 mm. Head golden-brown, orbital plates, interfrontal plates and frontal vitta yellow, antennae yellow. Frontal width 2.2–2.3×interfrontal height. Interfrontal bristles in 3–4 pairs, anterior-most pair(s) small, posterior two larger (middle pair largest and cruciate). Vibrissal angle with one large subvibrissal seta and 2–3 setulae; gena with very large upcurved seta and 15–17 setulae. Face ventromedially with triangular indentation; palpus with two subapical setae and several ventral setae. Antennal pedicel large, subequal in size to postpedicel; postpedicel slightly flattened and apically pointed. Eye height 1.9–2.2×genal height. Thorax dark brown to black. Five pairs of distinct dorsocentral bristles, anterior three pairs presutural, first two pairs 0.2–0.3 ×length of third; first postsutural pair separated by 12–14 rows of fine acrostichal setulae. Both postpronotal bristles large but inner bristle slightly smaller. Anepisternum with posterodorsal patch of 7–8 setae and 10–13 setulae; katepisternum with distinct anterior seta, very large posterior seta, several smaller setulae, and several large ventral setae. Scutellum rectangular, length 0.4–0.5 ×its width. Legs brown and yellow, femora with preapical yellow patch, fore tibia brown, mid and hind tibiae largely yellow with brown apex; apical three fore tarsomeres white, all other tarsomeres yellow. Mid tibia with eight dorsal bristles (four anterodorsal and four posterodorsal, all paired) in proximal half and three dorsal bristles (one anterodorsal, one dorsal, and one posterodorsal, no pairs) in distal half. Wing (Fig. 16A) infuscate with ill-defined pale spots and darker patches at the crossveins and around the center of most cells. CS2 1.5×length of CS3. R 4+5 sinuate, meeting costa at wing tip; costa ending at apex of R 4+5. M 1 pseudovein extending beyond dm-m almost to wing margin; M 4 extending beyond dm-m about halfway to wing margin; crossvein r-m just before midpoint of R 4+5, crossveins separated by 1.2–1.3 ×length of dm-m; CuA+CuP distinct but not tubular, and bent apically. Alula large, length 2.8–3.0 ×width, outer edge slightly sinuate.
MALE ABDOMEN (Figs 5D, 6B–C, 7–8). S5 broad, subrectangular with a slight anteromedial emargination and a very deep posteromedial emargination, posterior surface of each lobe with dense setation. S6+7 very large (almost subequal to epandrium) and complex: S6 extending ventrally under (dorsal to) S5 and with three thickened, posteriorly-directed lobes situated under (dorsal to) emargination of S5; posteriorly to this lies a folded sclerite, hourglass-like in shape with the fold occurring at middle (upper half is connected to the rest of S6 and lower half is free-hanging); S7 with elongate, dextral extension reaching across to and fused to ring sclerite; S8 with dorsal, anteromedial semicircular emargination; ring sclerite well-developed. Epandrium very large (only slightly smaller than head); cercus reduced to transverse strip along posteroventral margin of epandrium with several long setae; subepandrial sclerite X-shaped. Hypandrium triangular, anteromedial apodeme curved upwards anteriorly. Surstylus short and complex: anterior half composed of two lobes: a rectangular dorsal lobe which is bent inwards anterodorsally and a thickened, triangular, beak-like ventral lobe; posterior half subtriangular, bulging dorsolaterally, with a broad anterior point, an elongate posterior ‘arm’, and a broad, rounded ventral lobe which has many long setae on the outer surface and a patch of thickened setae along the inner surface. Postgonite elongate, tapered-triangular and apically slightly bent anteriorly. Phallapodeme elongate and slightly sinuate; basiphallus large, wedge-shaped (often visible between surstyli in dried specimens). Distiphallus extremely large (~12% total body length), divided into basal section and apical section: basal section strongly sclerotized and boot-shaped; apical section composed of a bent, trough-like, sinuate lower sclerite and a pair of flattened, curved lateral sclerites.
FEMALE ABDOMEN (Fig. 9). Postabdomen stout, segments 6–7 partially fitting into segment 5 at rest; when fully everted, postabdomen comprising ~30% of total abdominal length. T6–7 and S6–7 broad but short with 8–10 posterior setae. T8 divided into two broad, posteriorly long-setose, lateral plates. Epiproct very large (~40% total length of postabdomen), divided into two ovoid, setose sclerites, resembling very large cerci. Cercus small, ovoid with 4–5 long, sinuate setae. S8 broad, semicircular, with long setae in posterior half. Hypoproct well-developed, sub-pentagonal, with two setae, 14–17 setulae, and dense microtomentum in posterior third. Spermathecae stout, pear-shaped and lightly grooved with an elongate, slightly sinuate, subconical stem.
Remarks
Pleuroseta ingens sp. nov. is externally almost indistinguishable from, and internally very similar to, P. monteithi sp. nov. but it is distinguished by several characters of the male genitalia (S5 with a linear posteromedial emargination, S6 with three distinct, posteriorly-directed ventral lobes, and basal part of the distiphallus boot-shaped with an elongate apical extension).
Pleuroseta ingens sp. nov. is the most commonly collected species of Pleuroseta, comprising about 72% of the specimens we have seen (mostly from trap samples collected by G.B. Monteith and/or D.J. Cook).
description: Published as part of Kuwahara, Gregory K. & Marshall, Stephen A., 2023, A revision of the Australian genus Pleuroseta Richards (Diptera, Sphaeroceridae), pp. 69-97 in European Journal of Taxonomy 910 on pages 80-86, DOI: 10.5852/ejt.2023.910.2361, http://zenodo.org/record/10306494