Howickia robustaseta, Kuwahara & Marshall, 2022

Kuwahara, Gregory K. & Marshall, Stephen A., 2022, A revision of the Australian species of Howickia Richards (Diptera: Sphaeroceridae: Limosininae), Zootaxa 5192 (1), pp. 1-152 : 139-141

Howickia robustaseta sp. nov.

( Figs. 43.1–43.8 )

Description. Body length: Males 1.2–1.4 mm, females 1.3–1.5 mm.

Head: Orange-yellow to yellow-brown, microtrichose except for thin, shiny, golden rugose strips along either side of interfrontal plates; gena golden-yellow; antenna yellow-orange. Frontal width 2.0x interfrontal height, frontal vitta wide, frons bulging and with reticulate pattern. Two pairs of very stout interfrontal bristles preceded by a slightly smaller pair (0.6–0.7x length of posterior pairs); 1 lateroclinate orbital bristle and 3 minute anterior setulae. Ocelli absent and replaced by very fine, diverging setae. Gena with strong upcurved bristle and 2 finer setae, finely and densely striate, shiny, lower third microtrichose; vibrissa very thick, vibrissal angle with 2 smaller setae. Face slightly flattened along ventral margin; palpus capitate with 1 large apical seta. Eye height 1.6x genal height.

Thorax: Orange-yellow to yellow-brown, lateral edges lighter; scutum shiny despite microtrichia; katatergite dark brown. One pair of dorsocentral bristles; 9–10 rows of short, stout acrostichal setulae. Prosternum narrow, linear, posteriorly expanded. Scutellum shiny but heavily microtrichose, reddish, semicircular, its length 0.3x its width; 4 scutellar bristles long, basal pair 1.2x length of apical pair.

Legs: Orange-yellow, tibiae proximally and distally lighter; tarsi dirty white. Male mid tibia with a large apicoventral bristle. Basal half of mid tibia with 3 dorsal bristles (2 anterodorsal and 1 posterodorsal), distal half with 3 dorsal bristles (1 anterodorsal, 1 dorsal, and 1 posterodorsal).

Wing/halter: Halter absent.

Male abdomen: Reddish-brown, heavily sclerotized, shining black along posterior edges, postabdomen orangebrown. T2–5 and S2–4 uniformly long-setose along entire surface with large posterolateral setae. S5 broad but short (width 4.0x length), asymmetrical (right side 1.3x longer than left), uniformly long-setose with a posteromedial patch of short setae. Epandrium large, hemispherical, and densely long-setose; cercus slightly protruding, subtriangular with 3 long medial setae and several smaller setae. Hypandrium medially tapered, slightly sinuate; ventral lobe stout, apex curved posteroventrally; posterodorsal lobe elongate, originating from the posterior edge of the medial part. Surstylus subrectangular with a moderate constriction around the apical third, apex broadened with 3 stout apical thorn-like setae and several fine ventral setulae. Postgonite blade-like, angled forwards slightly at around midlength, anterior edge with several minute setulae. Phallapodeme elongate, slightly sinuate with a moderate dorsal fin along anterior half; basiphallus elongate, arms broadened apically with a small dorsoapical point. Distiphallus divided into two distinct sections: basal half with a large, saddle-like dorsal sclerite connected to a broad, triangular ventral sclerite; distal half with a broad, rectangular dorsal sclerite and a large, posteriorly constricted, saddle-like ventral lobe supporting a membranous apical flap.

Female abdomen: Reddish-brown, heavily sclerotized, shining black along posterior edges, T4–5 orangish. T2–5 and S2–5 uniformly long-setose along entire surface with large posterolateral setae; pleural membrane with small setal patch. Preabdomen slightly shorter in length to head + thorax. Postabdomen stout, 2.5x length of T5. T6 and T7 usually well-developed, present as broad rectangular plates bearing a posterior row of 6 setae; T7 sometimes reduced to 2 lateral plates. Epiproct rectangular with a small, triangular posteromedial tab and dorsomedially bearing a pair of setae. Cercus subtriangular with 4 long sinuate setae (1 apical, 2 lateral and 1 dorsal) and several smaller setulae. S6 and S7 usually well-developed, present as broad rectangular plates bearing posterior rows of 12 and 8 setae, respectively; T7 sometimes reduced to 2 lateral plates. S8 reduced to a broad, posteriorly microtrichose plate with 2 anterolateral tabs and a dorsomedial row of 6 setae. Hypoproct rounded, posteriorly microtrichose with a row of 4 stout setae. Spermathecae stout, hemispherical and deeply grooved; stem elongate (1.3–1.5x length of spermatheca) and tapered.

Material examined. Holotype: AUSTRALIA: New South Wales: Lord Howe Island, Mount Gower , 100 m, leaf litter, no date given, T. Kingston (♂, AMSA).

Paratypes: AUSTRALIA: New South Wales: Lord Howe Island, 15–60 m, Intermediate Hill , carrion trap, 19– 30.iv.1980, S.&J.Peck (1♂, 1♀, AMSA) ; Lord Howe Island, Eastern slopes of Roach Island , 31°30’07”S 159°04’08”E, 0–50 m, sclerophyll tall grass– Cyperus , pitfall trap, 29.xi–7.xii.2000 (4 ♂, 6 ♂, AMSA) ; Lord Howe Island, Mount Gower track, Site G31, 31°35’07”S 159°04’52”E, 790 m, Zygogynum / Dracophyllum forest, litter, 10– 17.v.2004, N. Velez (1 ♂, 1 ♀, AMSA) ; Lord Howe Island, Mount Gower , bottom of ridge north of igloo, 31°35’06”S 159°04’34”E, 812 m, pitfall trap, 18–31.i.2002, I. Hutton (8 ♂, 6 ♀, AMSA) ; Lord Howe Island, Mount Gower , bottom of southernmost gully, 31°35’17”S 159°04’23”E, 670 m, pitfall trap, 18–31.i.2002, I. Hutton (6 ♂, 11 ♀, AMSA) ; Lord Howe Island, Mount Gower , end of ridge, 31°35’10”S 159°04’23”E, 871 m, pitfall trap, 18–31.i.2002, I. Hutton (4 ♂, 6 ♀, AMSA) ; Lord Howe Island, Mount Lidgbird track, Site L 11, 31°33’39”S 159°05’26”E, 360 m, Drypetes / Cryptocarya litter, 1–12.xi.2004, N. Velez (2 ♂, 2 ♀, AMSA) ; Lord Howe Island, Summit of Mount Gower , 31°35’20”S 159°04’23”E, 850–900 m, closed gnarled mossy forest– Bubbia / Dracophyllum, pitfall trap, 22–28.xi.2000, no collector given (7 ♂, 11 ♀, AMSA) ; same data as holotype (3 ♂, 3 ♀, AMSA, DEBU) .

Other material examined: 360 additional specimens from Lord Howe Island, deposited in AMSA.

Etymology. This name is in reference to the thickened chaetotaxy of the head and thorax in this species. Thickened setae are common to many flightless species of sphaerocerid, but H. robustaseta has stouter chaetotaxy than any other wingless species of Howickia (Latin ‘robustus’: strong, stout, robust; Latin ‘seta’: bristle, hair).

Comments. Howickia robustaseta is readily distinguished from all other wingless species of Howickia in having thickened chaetotaxy and strongly reduced eyes. Additionally, it can be separated from other wingless species with a yellow head and thorax in lacking ocelli, replaced by very fine, diverging setae. The other wingless species of Howickia found on Lord Howe Island, H. nuda and H. tricolor , can be separated as follows: H. nuda has a very dark head and thorax, finer chaetotaxy, and lacks body microtrichia, and H. tricolor has a tricoloured body, small but distinct ocelli, and a bulging face.

Figures

FIGURES 43.1–43.5. Howickia robustaseta sp. nov. 43.1, male habitus, lateral; 43.2, male head, anterolateral; 43.3, male S5–8, ventral; 43.4, male terminalia, lateral; 43.5, aedeagus and associated structures, lateral. Scale bars indicate 0.5 mm.