Polytrichophora Cresson

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2012, A revision of the new world species of Polytrichophora Cresson and Facitrichophora, new genus (Diptera, Ephydridae), ZooKeys 231, pp. 1-116 : 14-16

Genus Polytrichophora Cresson

Polytrichophora Cresson 1924: 161. Type species: Polytrichophora agens Cresson 1924: 161, original designation. Cresson 1942: 114 [review of Nearctic species]; 1946: 143, 151 [review of Neotropical species, key]. Wirth 1965: 739-740 [Nearctic catalog]; 1968: 8-9 [Neotropical catalog]. Zatwarnicki and Mathis 2001: 50 [generic diagnosis].

Diagnosis.

Small to moderately small shore flies, length 1.4-3.5 mm; generally densely microtomentose, dull species (Figs 29-31). Head (Figs 29-30): Frons lacking anterior, proclinate, fronto-orbital seta; face substantially prominent at level of dorsal facial seta; antennal grooves generally sharply defined ventrally; facial setae usually comprising 8 setae, these not arising from shiny papilla and generally decreasing in size from dorsum to venter, appearing as 2 series (Figs 29-30) due to divergent orientation of setae in series; setae of primary series inclinate (setae 1, 2, 5, and 7), generally larger than setae of secondary series except for seta 2, which is much reduced and inserted laterad and sometimes slightly ventrad of seta 1, seta 1 largest of all facials, inclinate (cruciate with opposite seta), but not arising from shiny papilla; setae of secondary series oriented dorsolaterally to laterally (setae 3, 4, 6, and 8), usually smaller series than primary series; face lacking a distinctly dorsoclinate seta at ventral extremity; parafacial narrow to moderately wide, generally bearing setulae although sometimes fine and pale or lacking; gena variable but generally short to moderately high. Eye generally oval, conspicuously microsetulose, bearing numerous interfacetal setulae; maxillary palpus yellow. Thorax (Fig. 31): Single presutural and postsutural supra-alar setae well developed; postsutural supra-alar seta reduced, about 1/2 length of postalar seta; acrostichal setae present; notopleuron bearing several setulae in addition to 2 larger setae; anterior notopleural seta inserted conspicuously closer to posterior notopleural seta than to postpronotal seta. Wings transparent; costa bearing 3-5 long, dorsal setae between humeral and subcostal breaks. Forefemur normally developed, lacking row of short, stout setae along posteroventral surface; hindtibia lacking a preapical, ventral, spur-like seta. Abdomen: Tergites variable, but mostly unicolorous, if bicolorous, bearing pale colored areas laterally, but these not distinctly wedge-shaped; 4th tergite of ♂ only slightly longer than 3rd. Male terminalia (Figs 24-27): Epandrium complete or separate dorsally, in posterior view more or less elliptical, 2 × longer than wide, in ventral half gradually tapered, or pyriform, broader basally and tapered irregularly to apex, on whole surface bearing distinct setae, in lateral view apical half slightly widen by extension of its ventral portion, apical section of ventral margin often with setae; cerci fused ventrolaterally to medial margin of epandrium, in posterior view generally slightly elongate or hemispherical; gonites rod-shaped without setae, rarely lobate; aedeagus strongly elongate, about 4 –6× longer than wide, in dorsal view base generally narrowly triangular, apex rounded, in lateral view trunk of aedeagus with uniform thickness, apex pointed and generally bearing subapically a narrow, membranous flap that generally folds back under aedeagus with about 2/3 length of aedeagus to battered tape 2 × as long as aedeagus; hypandrium in dorsal view H-shaped, with transverse cross-bar, anterior arms arcuate, approximate to each other, with narrow arms with uniform thickness or unequal lobate broadened, sometimes to different degree at apex interrupted or/and with reduced cross-bar, in lateral view hypandrium flat, slightly directed dorsally; phallapodeme separate from aedeagus, in posterior view elongate with extension at base and bifurcate anteriorly, in lateral view subtriangular or subrectangular, with dorsal margin slightly bent ventrally, ventral margin irregularly U-shaped, middle part of apodeme with ventral broad appendix, sometimes slightly directed anteriad; ejaculatory apodeme absent.

Distribution.

This is one of the few genera of Ephydridae that occurs worldwide and in temperate or tropical environments. The New World, with 23 species, currently has greater species diversity. Worldwide there are 35 species.

Natural history.

Specimens of Polytrichophora are usually associated with mud-shore and sand-shore habitats ( Deonier 1965) or rarely with a marsh-reed habitat ( Scheiring and Foote 1973). We usually found greatest diversity and abundance while collecting on mud and sandy shores that had a mat-like covering of algae. Some species, as will be noted with their individual treatment, are tolerant of mildly saline conditions and occur on mud and sandy shores where the water is brackish.

Discussion.

Polytrichophora , along with Discocerina , Facitrithophora , and Hydrochasma Hendel (New World genera), form a monophyletic lineage within the Discocerinini , as noted previously under the tribal diagnosis. Polytrichophora may be distinguished from other genera of the Discocerina group by the following synapomorphies: (1) facial setae with a secondary series of dorsolaterally inclined setae laterad to inclinate primary series (Figs 29-30); (2) parafacial setulose (Figs 29-30); (3) gena short to moderately high (Fig. 30); (4) eye densely pilose; (5) cerci usually fused ventrally or ventrolaterally with epandrium; (6) epandrium with dorsal portion above the cerci weakened, thin, or absent; (7) anterior margin of hypandrium deeply incised; (8) subapical ventral aedeagal appendix (the plesiomorphic condition is an aedeagus without appendices).

Key to species of Polytrichophora from the New World

The conciliata group

Species included:

Polytrichophora adarca sp. n., Polytrichophora agens Cresson, Polytrichophora arnaudorum sp. n., Polytrichophora barba sp. n., Polytrichophora conciliata Cresson, Polytrichophora flavella sp. n., Polytrichophora marinoniorum sp. n., Polytrichophora rostra sp. n., Polytrichophora setulosa Cresson, Polytrichophora sinuosa sp. n.

Discussion.Synapomorphies for the conciliata group are: phallapodeme bar-like and separated from hypandrium; hypandrium small, H- or C-shaped. Within the conciliata group there are two assemblages of species based primarily on the shape of the epandrium in lateral view. The first assemblage, which includes Polytrichophora agens Cresson, Polytrichophora barba , Polytrichophora flavella , Polytrichophora rostra , Polytrichophora setulosa Cresson, is characterized by a wide hypandrium that bears a shallow and arched posterior margin with long apical arms (reduced in Polytrichophora agens ). Suggested relationships among these species in parenthetic notation are: Polytrichophora barba ( Polytrichophora rostra , Polytrichophora setulosa Cresson) ( Polytrichophora agens Cresson, Polytrichophora flavella ). An apomorphy for Polytrichophora barba is the presence of a dense tuft of setulae on the epandrium. Specimens of Polytrichophora rostra and Polytrichophora setulosa have a crescent-shaped ventral epandrial process (surstylus) and have pronounced asymmetry of the anterior hypandrial arms. Specimens of Polytrichophora agens and Polytrichophora flavella have an asymmetrical epandrium.

The second assemblage, which includes Polytrichophora adarca , Polytrichophora arnaudorum , Polytrichophora conciliata Cresson, Polytrichophora marinoniorum , Polytrichophora sinuosa , is characterized by a small H-shaped hypandrium in ventral view, and the relationships of its included species in parenthetic notation are: Polytrichophora arnaudorum ( Polytrichophora adarca (( Polytrichophora conciliata Cresson, Polytrichophora marinoniorum ) Polytrichophora sinuosa ))). An apomorphy for Polytrichophora arnaudorum is the long anterior process of the aedeagus (basiphallus). For other species of this group, there is a narrow ventral epandrial process (surstylus). Specimens of Polytrichophora adarca have a shortened ventral epandrial process (surstylus). For other species, there is a lateral projection on the distiphallus and a narrowed anterior process of the aedeagus (basiphallus). Specimens of Polytrichophora conciliata Cresson and Polytrichophora marinoniorum have a digitiform ventral epandrial process (surstylus), and Polytrichophora sinuosa has an elongated ventral epandrial process (surstylus).