Procanace dianneae Mathis

Mathis, Wayne N. & Marinoni, Luciane, 2012, A conspectus on the Canacidae (Diptera) of Brazil, ZooKeys 162, pp. 59-92: 74-75

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Procanace dianneae Mathis


Procanace dianneae Mathis  Figs 9-11

Procanace dianneae  Mathis 1988: 330 [United States. Virginia. Westmoreland: Westmoreland State Park (banks of Potomac River); figs. of ♂ terminalia; HT ♂; USNM]; 1989: 606-607 [review]; 1992: 11 [world catalog]. Munari and Mathis 2010: 25 [world catalog].


Externally this species is very similar to those of the cressoni group, and we are tentatively placing it in that group. It differs from the two species of that group, Procanace cressoni  Wirth and Procanace taiwanensis  Delfinado, as well as other congeners by the following combination of characters: Moderately small to medium-sized beach flies, body length 2.00-3.10 mm; general coloration whitish gray, olivaceous to brown, scutum darker. Head: Postocellar setae well developed, subequal in length to ocellar setae; clypeus low, height 1/4 width; palpus yellowish. Thorax: Scutum mostly bluish black, sparsely microtomentose, scutum densely microtomentose, brown; proepisternal seta present, pale; katepisternal seta present; acrostichal setae absent. Abdomen: Unicolorous, olivaceous gray with some faint brownish coloration. Male abdomen as follows: Sternite 4 (Fig. 11) narrowly rectangular, over 2X as long as wide; sternite 5 (Fig. 11) wider than long, width of anterior margin subequal to that of sternite 4, becoming wider posteriorly, lateral margins irregular, widest at posterior margin, bearing a short process posterolaterally; epandrium wider than high in posterior view, bearing numerous setae, in lateral view (Fig. 10) posterodorsal margin broadly rounded, ventral margin nearly flat, anterior margin nearly straight except for anteroventral prong and irregular dorsal 1/3; surstylus (Figs 9-10) as 2 processes, anterior one much smaller, digitiform, bearing several setulae preapically and apically, posterior process much larger, length nearly equal to that of epandrium and equally as wide, in lateral view with posterior margin irregularly arched, anteroventral process very angulate in lateral view and spatulate in posterior view.

Specimens examined from Brazil.

PARANÁ. Antonina (25°27.1'S, 48°41.1'W; beach; Ponta da Pita), 3 Feb 2010, D. and W. N. Mathis (3♂; DZUP, USNM); Antonina (25°28.4'S, 48°40.9'W; beach/mangal), 3 Feb-14 Nov 2010, D. and W. N. Mathis (13♂, 4♀; DZUP, USNM); Paranaguá (Rio Itiberê; 25°31.4'S, 48°30.3'W; 3 m), 23 Jan 2010, D. and W. N. Mathis (4♂, 2♀; DZUP, USNM).

RIO DE JANEIRO. Ilha da Marambaia (23°3.6'S, 43°59.1'W), 4 Sep 2000, D. and W. N. Mathis (11♂, 3♀; USNM).

SÃO PAULO. Ubatuba, Praia do Estaleiro (23°20.5'S, 44°53'W; beach), 30 Mar 2010, D. and W. N. Mathis (6♂, 1♀; DZUP, USNM).


Nearctic: Bermuda, United States (Alabama, Delaware, Florida, Maryland, Mississippi, North Carolina, South Carolina, Virginia). Neotropical: Brazil ( Paraná, Rio de Janeiro, São Paulo), West Indies (Cuba).

Natural History.

All specimens of the type series were collected from the shoreline of the tidal portion of the Potomac River at Westmoreland State Park (Virginia, United States). At the park, the river is over a mile wide, and the water is slightly brackish due largely to the tidal influence. The shore is either almost entirely sandy, the bathing area of the beach, or a combination of sand, considerable gravel, and some cobble and large rocks. In the latter habitat, the shore is quite narrow, at most two to three meters, and immediately adjacent to the shore is a cliff. In the sandy area, specimens occurred along the protected sides of narrow, wooden jetties that were installed perpendicular to the shoreline to break up the action of waves and prevent erosion of the beach. In the sand/cobble/rock habitat, specimens were found only on rocks and were easily collected by sweeping immediately over and between the rocks. Most of the rocks and jetties were covered in part with algae, and we suspect that the larvae of this species were feeding on them.


Much of the temperate and tropical Atlantic Coast of the New World has some of the busiest commercial waterways in the world, and we do not dismiss the possibility that this species was introduced in conjunction with the large volume of traffic on these waters.

This species has a demonstrated ability to disperse well. Although initially discovered in Virginia, where it occurs widely along the state’s maritime coast, the species has now been found from Delaware south to Florida, along the Gulf Coast (Alabama and Mississippi), and into the Neotropics (Cuba and Brazil). The records from the state of Paraná are the southernmost thus far.