Phrudoneura Meuffels & Grootaert

Bickel, Daniel J., 2013, Phrudoneura (Diptera: Dolichopodidae) from Australia and Melanesia, Zootaxa 3680 (1) : -

Genus Phrudoneura Meuffels & Grootaert

Phrudoneura Meuffels & Grootaert, 1987: 319 . Type species: Sympycnus (Phrudoneura) abbreviatus Meuffels & Grootaert, 1987 , by original designation.

Diagnosis. Body length ranges from 1.8–3.3 mm, but most species about 2.2–2.8. General: body colour variously yellow to dark brown.

Head: head almost circular in anterior view, but slightly wider than high; dorsal postcranium flat, and slightly concave dorsally; postorbitals uniseriate; pair converging postverticals present, positioned mediad of postorbital row; pair strong vertical and pair strong diverging ocellar setae present; both sexes with eyes widely separated by face and clypeus; clypeus not tectiform; male eye facets more or less uniform with tiny hairs between facets; palp with distinct apical seta; scape usually bare dorsally; first flagellomere enlarged subtriangular to subrectangular, and covered in microtrichia; arista arising dorsobasally on first flagellomere, with short hairs, and about as long as head height.

Thorax: posterior slope of mesonotum flattened but not depressed; ac biseriate, comprising 8–10 regular pairs; 5 dc present, slightly decreasing in size anteriorly; field of short setae present on anterior slope of thorax; 1 pa, 2 sa (anterior sa much shorter than posterior sa), 2 sr, 2 npl, 1 hm, 1 pm present; median scutellar seta strong, lateral scutellar present as weak seta, about one-fifth size of median; proepisternum with short black seta dorsally (usually not visible since covered by head), and with stronger black ventral seta above join with CI.

Legs: CI with short anterior setae and 3 longer distal setae; CII with short anterior setae and with two setae along distolateral ridge; CIII with strong lateral seta near 1/3, and trochanter III with short lateral seta; FI with short av and pv seta at 5/6; TI usually with ad-pd setal pair near 1/3, with ad seta stronger than pd seta, and with short ad setal serration from 1/3 to apex; FII and FIII with strong anterior subapical seta, and usually with short subapical av and / or pv seta; TII usually with three distinct ad-pd setal pairs; TIII with 3–4 distinct ad-pd setal pairs, and with two strong ventral setae; IIIt2 distinctly longer than IIIt1.

Wing: membrane hyaline; R2+3 ends in anterior margin at 5/6; R4+5 ends just anterior to apex; R4+5 and M diverging slightly from base; M without flexion (“ bosse alaire ”) in both sexes; male vein M ends in membrane halfway between dm-cu crossvein and wing apex (MSSC); female vein M extends to margin usually just before wing apex, and sometimes very slightly bowed with respect to R4+5; CuAx ratio near 0.5; anal angle weak.

Abdomen: hypopygium mostly withdrawn from view but capable of extension so well free of body; tergum 6 bare, narrow, hoodlike; segment 7 bare with longer tergum and shorter sternum; sternum 8 ovate with distinctive inverted V-shaped internal carina at base, and covering over left basal hypopygial foramen; epandrium subcircular in lateral view; ventral distal margin of epandrium with 3 pedunculate setae (= epandrial lobe setae), sometimes on raised ledge (e.g., Figs 1 a, b) otherwise arising on the surface of the epandrium ( Figs 3 a, b); surstylus short, bearing various setae and often modified pinnate seta; subepandrial sclerite subrectangular with row of dorsal setae; cercus subtriangular; female oviscapt divided into two hemitergites, each with crest of four spinelike setae.

Remarks. Although Phrudoneura currently comprises only ten described Australasian species (treated here), it is also widespread across the tropical Orient. Meuffels and Grootaert (2002) noted undescribed species from West Papua ( Indonesia), Thailand, and peninsular Malaysia, and I have seen additional undescribed species based on males from Sarawak (BMNH), Vietnam (BPBM), and poorly preserved males from the Papua New Guinea Highlands (Telefomin at 1450 m, and Mt Missim at 1300 m, BPBM).

Thus, Phrudoneura appears to be a widespread Oriental and Australasian genus, although the Oriental fauna remains undescribed. The genus appears to have its eastern limit in the Solomon Islands and New Caledonia, and it was not found in the intensively sampled rainforests of Fiji.

Phrudoneura is a prominent element in the New Caledonia fauna, where it is both diverse and commonly collected. Most of the collection sites in New Caledonia appear to be rainforest, and some of the species appear to be active even in the winter months. By contrast, the genus appears to be less commonly collected in Australia, and in addition to rainforest habitats, the gensu has also been collected in mangroves, along creeks in the arid zone, and in marshland.

Phrudoneura shows some similaritiy to the subfamily Sympycninae based on the following characters: posterior mesonotum not strongly flattened, dorsal postcranium flat or slightly convex, femora II and/ or III with distinct anterior preapical seta, reduced anal angle, and tibia I often with ad row of short setae (serration) on distal half; hypopygium usually held encapsulated by pre-abdomen (athough see discussion below). However additional morphological characters related to the taxonomic placement of Phrudoneura need to be discussed:

1. The head of Phrudoneura is subcircular in anterior view, and slightly wider than high. In contrast, most Sympycninae have the head usually ovate in anterior view, distinctly higher than wide. Also, most male Sympycninae have a distinctly narrowed face with enlarged anterior enlarged facets, while male Phrudoneura have a wide, parallel-sided face.

2. As noted before, males have vein M shortened and ending in the membrane halfway between the dm-cu crossvein and the wing apex (MSSC), while females have vein M reaching the wing margin just behind the apex. This is the best diagnostic generic character for male Phrudoneura .

3. In both sexes, vein M is perfectly straight and lacks a distinct flexion (or bosse alaire) anywhere along its length. This is important because most other Sympycninae have such as distinct flexion with associated depression in the membrane usually postioned midway between crossvein dm-cu and the wing apex.

4. In most Sympycninae , segment 7 is short and not pedunculate. However in Phrudoneura , tergite 6 and segement 7 are bare, and segment 7 forms a short peduncle for the hypopygium. Therefore, although the hypopyium is usually held retracted or encapsulated by segment 5, it can also be projected outwards with the peduncle. This peduncle suggests affinity with the rather loosely defined agglomeration of genera known as the Peloropeodinae , some of which also have a short hypopygial peduncle.

5. Male sternite 8 (the hypopygial cap) usually has a V-shaped internal sclerotization, evident in cleared specimens (e.g., Figs 1 b, 3a–c). This is similar to sclerotization of sternite 8 in Acropsilus Mik (see figures in Bickel, 1998), and in the genus Nepalomyia Hollis.

6. The epandrium is subcircular in lateral view, while most genera in the Sympycninae have a more rectangular epandrium.

7. The curved ventral margin of the epandrium has a row of three usually pedunculate setae, and these are often on a slightly raised projection. I believe this genitalic character is diagnostic for the genus Phrudoneura . The basal two setae are strong and are probably homologous with the two setae found on the epandrial lobe in many dolichopodid genera. The shorter distal seta may be homologous to a short seta often found near the base of the epandrial lobe in other dolichopodid genera.

8. The surstylus is usually short, bearing short arms with modified setae.

9. A distinct subepandrial sclerite, usually subrectangular with some dorsal setae, is present in many species ( Figs 1 a-b) just ventrad of the two cerci.

10. The female oviscapt is divided into two hemitergites, each with a crest of four spine-like setae or acanthophorites. This is a common pattern in the Sympycninae as well as other Dolichopodidae .

Phrudoneura is perhaps close to to the Sympycninae , but it is somewhat distant from the main polythethic genus Sympycnus Loew based on characters 1, 3, 4, 5, 6 and 7, discussed above. Indeed, some characters (4 and 5 above) would suggest a possible relationship with Acropsilus Mik (see further discussion in Bickel, 1988). In light of this, rather than place Phrudoneura i n the Sympycninae and further dilute the definition of the subfamily, I regard the genus as incertae sedis within the Dolichopodidae .

The shortened male vein M is a distinctive and readily recognized autapomorphy for the genus Phrudoneura . One would assume an ancestral or sister taxon would have the plesiomorphic state of a complete male vein M. As well, males of species within the Phrudoneura clade might not display this apomorphic character, and revert to the plesiomorphic state of a complete vein M. So how might one recognized closely related taxa with a complete vein M? The male genitalic structure as represented by characters 4–8 above might provide additional strong evidence of relationship.

At the basic taxonomic level, most species within Phrudoneura are dull coloured and lack distinctive MSSC (especially leg MSSC found in many Sympycninae ), and therefore delimitation of species groups within the genus might prove difficult.

Figures

FIGURE 1. Phrudoneura abbreviata Meuffels & Grootaert; a. hypopygium, left lateral. P. collessi sp. nov.; b. male postabdomen, left lateral. Scale line = 0.1 mm. Legend: cer = cercus; els = epandrial lobe setae; hyp, hypandrium; pha = phallus; sub = subepandrial plate; sur = surstylus.

FIGURE 3. Phrudoneura hibernalis sp. nov.; a. hypopygium, left lateral. P. adusta sp. nov.; b. male postabdomen, left lateral. Scale line = 0.1 mm.