Canacinae

Mathis, Wayne N. & Marinoni, Luciane, 2012, A conspectus on the Canacidae (Diptera) of Brazil, ZooKeys 162, pp. 59-92 : 63-64

Subfamily Canacinae

Canaceinae . Hendel 1913: 93 [as a subfamily of Ephydridae , incorrect formation of the subfamily-group name].

Canacinae . Enderlein 1914: 326 [as a subfamily of Ephydridae ]. Malloch 1933: 4 [as a subfamily of Ephydridae ]. Mathis 1982: 2 [as a subfamily of Canacidae , phylogeny]. McAlpine 2007: 43 [review, diagnosis, status]. Munari and Mathis 2010: 11-27 [world catalog].

Diagnosis.

Adult. Minute to moderately large surf flies, body length 1.60-5.00 mm; blackish, brownish, yellowish, or gray, often invested with whitish to grayish microtomentum. Head: Antennae broadly separated, inserted more or less on protuberant facial tubercles; subcranial cavity large; 3-5 lateroclinate fronto-orbital setae. Face slightly convex to concave; setae usually sparse except for mesoclinate vibrissal seta; vibrissal angle unmodified; clypeus prominent, enlarged, wide. Gena high, bearing 1-4 dorsoclinate genal setae. Subcranial cavity enlarged; labella short, nongeniculate; prementum short, broad, deeply incised distally, distinctly emarginated apically; tentorial arms of head capsule enormously developed and strongly sclerotized. Thorax: Mesonotum with 4 or more dorsocentral setae. Wing usually hyaline; C extended to M and with subcostal break only; Sc complete and separate from R1 almost to its apex; cells br, bm, dm, and cup complete; A1 short. Precoxal bridge present. Abdomen: Male tergites 1-6 exposed; spiracles 1-6 in posteroventral portion of tergite, spiracle 7 also in tergite 6; terminalia symmetrical; surstylus fused with epandrium; hypandrium usually with lateral arms extended above aedeagus, fused into posteriorly directed process; aedeagus relatively short; cercus usually weak. Female cerci well sclerotized, long, approximate, bearing a strong apical seta, sometimes preceded by similar but smaller setae; ventral wall of genital chamber with V- or ring-shaped sclerite; spermathecae 2.

Egg. Simple, ovoid; with microscopic reticulations.

Third-instar larval length 5-6 mm; tapered anteriorly and posteriorly from about 4th abdominal segment and terminated posteriorly in a slender retractable respiratory tube. Abdominal segments 2-7 with creeping welts. Prothoracic spiracle a slender retractable filament. Posterior spiracles with 3 oval spiracular openings arranged with longitudinal axis at slightly less than right angles to adjacent opening; each spiracular plate with 4 tufts of interspiracular setae. Cephalopharyngeal skeleton with ventral cornu truncate, appearing broken at apical margin; mandibles approximate anteriorly, separated posteriorly by small V-shaped accessory oral sclerite; anterior ventrolateral extensions of tentoropharyngeal sclerite narrowly fused with ventral bridge of hypopharynx; parastomal bars prominent, united by a thin fenestrated epipharyngeal sclerite.

Puparium. Brown, similar in size and form to third-instar larva, rather spindle-shaped, curved at each end; integumental spinules more prominent than on larva and anterior respiratory processes fully extended.

Biology.

All Canacinae from the New World occur in intertidal habitats and are sometimes called surf flies. Although the natural history of the subfamily is poorly known, the larvae and adults are probably grazers on algae or are saprophytic in both saline and freshwater habitats. In Brazil, all species of the subfamily Canacinae occur in the littoral biotic region.

Discussion.

Adult of Canacinae are similar and sometimes confused with shore flies ( Ephydridae ) and most species described in the 19th century were placed in the Ephydridae . Canacids are distinguished by the wing venation (cells bm and cup complete) and by the additional abdominal segments (5 in ephydrid males, 6 in canacids), which in females terminate as an elongate and fused epiproct+cercus that bears enlarged, apical setae.

The Canacinae now include 122 valid species that are placed in 11 genera ( Wirth 1951; Mathis 1992; Munari and Mathis 2010). The New World fauna comprises five genera and 35 species ( Wirth 1965, 1975, 1987; Mathis 1992). No fossils are known. Mathis’ catalog (1992) included all species then known plus references to papers containing keys and illustrations. The recent catalog of Munari and Mathis (2010) is a complete updating, including keys to all known genera. In the New World, Mathis (1989, 1997) reviewed the surf-fly fauna for the Caribbean and Gulf of Mexico.

Mathis (1982) proposed a classification for the Canacinae sensu stricto that should be revised. The subfamily includes two tribes, Canacini and Nocticanacini . The Canacini are represented in the New World by a single genus, Canacea Cresson, which belongs to the subtribe Dynomiellina . The Nocticanacini are represented by three genera in the New World, Canaceoides Cresson, Nocticanace , and Paracanace . Procanace , the fifth New World genus, was initially placed in Nocticanacini , but it is now evident that this genus is the sister group to all other genera of the subfamily Canacinae .

Key to Genera of Canacinae from Brazil