Pleuroseta monteithi, Kuwahara & Marshall, 2023

Kuwahara, Gregory K. & Marshall, Stephen A., 2023, A revision of the Australian genus Pleuroseta Richards (Diptera, Sphaeroceridae), European Journal of Taxonomy 910, pp. 69-97 : 86-91

Pleuroseta monteithi sp. nov.

urn:lsid:zoobank.org:act:9321FA5F-A43E-4B05-8C88-E661260B9E23

Figs 5E , 10–11 , 16B

Etymology

This species name is in honour of Dr Geoff Monteith, who collected the type specimens of this species as well as most of the other known specimens of Pleuroseta .

Material examined

Holotype

AUSTRALIA • ♂; Queensland, Cape Tribulation, transect site 8 ; 16°05' S, 145°26' E; 18 Nov. 1998; G.B. Monteith leg.; dung trap, 6 am –6 pm; QMBA debu00160870 .

Paratype

AUSTRALIA – Queensland • 1 ♂; same collection data as for holotype; DEBU .

Description

BODY ( Fig. 10A ). As described for P. ingens sp. nov., except as follows: length 3.7–3.8 mm. Frontal width 2.4–2.5 ×interfrontal height. Gena with 11–14 setulae. First postsutural pair of dorsocentral bristles separated by 9–10 rows of fine acrostichal setulae. Anepisternum with posterodorsal patch of 5–6 setae and 10–12 setulae. Wing pattern ( Fig. 15B ) slightly paler than in P. ingens . CS2 1.3×length of CS3.

MALE ABDOMEN ( Figs 5E , 10B–C , 11 ). S5 broad, subrectangular with large, triangular, posteromedial emargination, posterior surface of each lateral lobe with a dense tuft of fine, curved setae. S6+7 large (almost subequal to epandrium) and complex: S6 extending ventrally under (dorsal to) S5 and with dark, T-shaped posterior extension, the apex of which has a rippled margin; dorsal to this lies a tubular, basally constricted sclerite with heavily sclerotized, flattened, disc-like apex; S7 with elongate, dextral extension reaching across to ring sclerite; S8 with dorsal, anteromedial semicircular emargination; ring sclerite well-developed. Epandrium very large (only slightly smaller than head); cercus indistinct from epandrium; subepandrial sclerite thick, X-shaped. Hypandrium triangular, anteromedial apodeme curved upwards anteriorly. Surstylus short and complex: anterior half composed to two lobes: a semicircular dorsal lobe which is bent inwards anterodorsally and a thick, triangular, beak-like, ventrally setose ventral lobe; posterior half subtriangular, bulging laterally, 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, triangular and slightly bent forwards apically into a small hook. Phallapodeme elongate and curved; basiphallus large and saddle-shaped (often visible between surstyli in dried specimens). Distiphallus extremely large (~11% total body length), divided into basal and apical sections: basal section elongate, sclerotized and curved, with small lower knob articulating with apical section and spinose, membranous upper apex; apical section composed of a bent, trough-like, sinuate lower sclerite and a pair of flattened, curved lateral sclerites which fit along inner surface of lower sclerite.

FEMALE ABDOMEN. Female unknown.

Remarks

Pleuroseta monteithi sp. nov. is externally almost indistinguishable from, and internally very similar to, P. ingens sp. nov. As such, the male genitalia are required to identify this species: S5 with a triangular posteromedial emargination, S6 with a flattened, T-shaped posterior extension, anterior lobe of surstylus with a more elongate triangular ventral lobe and a semicircular dorsal lobe, postgonite thicker and straighter along the anterior margin, and basal part of the distiphallus more evenly curved without an elongate apical extension.

Both known specimens of Pleuroseta monteithi sp. nov. were collected some 150 km north of the northern-most collection locality of the similar P. ingens sp. nov. (from Mount Hypipamee National Park), suggesting that they might be allopatric or parapatric sister species.

Figures

Fig. 5. A. Pleuroseta occidentalis sp. nov. paratype, left wing, ventral view (debu00244165). B. Pleuroseta occidentalis paratype, hypandrium, dorsal view (debu00245797). C. Pleuroseta wentworthi (Richards, 1973), hypandrium, dorsal view (debu00264733). D. Pleuroseta ingens sp. nov. paratype, hypandrium, dorsal view (debu00160984). E. Pleuroseta monteithi sp. nov. paratype, hypandrium, dorsal view (debu00160892). Scale bars: A=0.50 mm, B–E=0.10 mm.

Fig. 10. Pleuroseta monteithi sp. nov. A. Male holotype habitus, lateral view (debu00160870). B. Male paratype terminalia, lateral view (debu00160892). C. Male paratype terminalia, posterolateral view (debu00160892). Abbreviations: epa =epandrium; hyp =hypandrium; se =subepandrial sclerite; ss =surstylus. Scale bars: A = 1.0 mm; B–C =0.40 mm.

Fig. 11. Pleuroseta monteithi sp. nov. paratype (debu00160892). A. Aedeagus and associated structures, lateral view. B. Male S5–8, ventral view. Abbreviations: bp = basiphallus; dp =distiphallus; pg =postgonite; phal=phallapodeme; rs =ring sclerite. Scale bars: A=0.40 mm; B= 0.60 mm.

Fig. 16. Pleuroseta left wings, ventral view. A. Pleuroseta ingens sp. nov. paratype (debu00162128). B. Pleuroseta monteithi sp. nov. paratype (debu00160892). C. Pleuroseta wentworthi (Richards, 1973) (debu402972). Scale bar: A–C= 0.5 mm.

Fig. 15. A. Pleuroseta wentworthi (Richards, 1973) holotype, ♂, habitus, lateral view. B. Pleuroseta dorrigonis (Richards, 1973) holotype, ♂, habitus, lateral view. Scale bar: A–B =1.0 mm. Photo credit: N. Tees and R. Cox (AMSA).