Canace ophiusae, Munari, Lorenzo & Almeida, Jorge Mota, 2014

Munari, Lorenzo & Almeida, Jorge Mota, 2014, A new species of Canace Haliday from Portugal, with a revised key to species (Diptera: Canacidae: Canacinae), Zootaxa 3873 (2), pp. 195-200 : 196-200

Canace ophiusae sp. nov.

( Figs 1–4 )

Diagnosis. This species is distinguished from congeners mainly by the following combination of characters: body length 2.53–3.26 mm; head with mesofrons bearing 2 large, subequal in length and strength, marginal, proclinate setae; major posterior seta inserted about in line with median ocellus, major anterior seta inserted about between the middle of frons and median ocellus; gena bearing 2 subequal, anaclinate, long setae just below the eye, and 1, occasionally 2, more ventrally placed, small, thin seta between the two major anaclinate setae; 2 anteroclinate genal setae toward the anterior margin, one larger seta inserted at anterior margin, the other one, distinctly shorter and thinner, inserted slightly posteroventrad; gena 0.85–0.91 times eye height; acrostichal setulae of mesonotum sparse to arranged in 4 rows, mostly inconspicuous to moderately developed; wing distinctly infuscated; wing length 2.31–2.70 mm; costal vein ratio averaging 0.15; vein M ratio averaging 0.60; surstylus, in lateral view, large, broadly subquadrangular to subrectangular, with a posteroventral fingerlike process.

Description. Moderately small beach fly, body length 2.53–3.26 mm; mostly dark coloured, with scutum sometimes showing distinctly purplish tinges dorsally, golden on both sides.

Head (fig. 1). Large, subquadrangular in lateral view; anterodorsal portion of head, near juncture with antenna, not protrudent; 1 pair of long, divergent ocellar setae and 1 pair of slightly longer, divergent pseudopostocellar setae, the latter inserted in vertical line with ocellar setae; a few scattered setulae between ocellar and pseudopostocellar setae; medial vertical and lateral vertical setae subequal in length; 3 long, lateroclinate, frontoorbital setae subequal in length, with a few minute setulae between them; colour of mesofrons and fronto-orbits similar, coppery to golden, the former somite with more or less obvious purplish tinges, or evenly golden; mesofrons bearing 2 large, subequal in length and strength, marginal, proclinate setae and 1 anterior, as well as 1 posterior, marginal tiny setulae, major posterior seta inserted about in line with median ocellus, major anterior seta inserted about between the middle of frons and median ocellus; antenna black; face, parafacial, and gena silvery grey, but dark grey to blackish if viewed ventrolaterally; gena bearing 2 subequal, anaclinate, long setae just below the eye, and 1, occasionally 2, more ventrally placed, small, thin seta between the two major anaclinate setae; in addition to the large vibrissa, 2 anteroclinate genal setae present towards the anterior margin, one larger seta inserted at anterior margin, the other one, distinctly shorter and thinner, inserted slightly posteroventrad; 0–3 short peristomal setae; gena 0.85–0.91 times eye height (measured medially); eye with oblique orientation; clypeus broadly exposed; buccal parts strongly sclerotized, as usual for the genus.

Thorax. Scutum with distinctly purplish tinges dorsally to evenly golden or coppery, always golden on both sides; pleural sclerites dark grey, with greenish to golden tinges, or almost entirely olivaceous; 1+3 dorsocentral setae; acrostichal setulae sparse to arranged in 4 rows, mostly inconspicuous to moderately developed, excepting the acrostichal prescutellar setae, which are very long and strong; 2 postpronotal setae, each with different orientation; 2 notopleurals, about subequal in length; 1 presutural; 1 supra-alar; 2 postalar setae, lateral one distinctly longer and stronger; scutellum with 1 apical and 1 basal, marginal pair of long setae, and 1 pair of moderately long setae on disc, about between base of scutellum and apical setae; 1 proepisternal; 1 proepimeral; anepisternum with 2–3 posteriorly oriented, postero-marginal setae and 1 small, upward oriented, posterodorsal seta; posterior half of anepisternum bearing many scattered setulae; katepisternum with sparse setulae only. Wing. Brownish infuscated; wing length 2.31–2.70 mm; vein topography basically typical for the genus; costal vein ratio averaging 0.15; M vein ratio averaging 0.60. Legs. Entirely dark grey to olivaceous, bearing setal vestiture more developed in male; forefemur with some long setae posterodorsally and posteroventrally, the latter distinctly longer; midfemur with anteroventral and posteroventral rows of thin setae, more obvious in male; tibiae evenly setulose, excepting a row of long posterodorsal setae on fore- and midtibiae, and dorsal to anterodorsal setae on hindtibia, the latter with an obvious, small, dark brown, shiny patch dorsoapically, a character state present in all species of the genus.

Abdomen. Brown to dark grey, often with an obvious olivaceous tinge, sparsely setulose, bearing long posteromarginal setae on each tergite. Male terminalia (figs 2–3): surstylus, in lateral view, very large, broadly subquadrangular to subrectangular, with a posteroventral fingerlike process; posterodorsal angle of surstylus bearing a tuft of long, moderately spaced setae; thin setulae are present along the anteroventral and posterior margins, as well as on the inner side of the posteroapical process. Female terminalia: cercus typical for the genus, slender, bearing an acutely pointed, spinelike seta apically.

Type material. The holotype ♂ of Canace ophiusae sp. nov. is labelled “[printed white label] PORTUGAL, Parede (nr. Lisbon) / rocky shore with tide pools, / 38°41’9.179”N – 9°21’18.126”W / 15.vi.2014, J. Almeida leg. // [printed red label] HOLOTYPUS / Canace ophiusae sp. nov. ♂ / L. Munari & J.M. Almeida des.”. Twelve paratypes (9 ♂♂ 3 ♀♀) bear the same locality data as the holotype, while three additional paratypes (NHM collection, London) bear the following data: Portugal, Parede, 11.vii.1961, E.A. Fonseca [Pres. by E.C.M. Assis Fonseca, BMNH 1988–212]; below a female paratype collected by Fonseca there is a small handwritten label which reads: “? Parhydra ” [sic].

The holotype was dry prepared from alcohol and then double mounted, micropinned in a plastic block. The specimen is in excellent condition, with the abdomen in situ, in that the large surstyli of the terminalia are widely exposed and, therefore, well visible. The holotype is deposited in the collection of the Natural History Museum, Venice (type inventory: MSNVE 5155). All paratypes collected in 2014 are deposited in the authors’ collections (Munari’s collection is property of the Natural History Museum, Venice), whereas the three specimens caught in 1961 are deposited in the collection of the Natural History Museum, London.

Distribution. Palaearctic: Portugal.

Etymology. The species epithet, ophiusae , derives from Ophiusa, also spelled Ophiussa, which is a former toponym given by the ancient Greeks to what is now Portuguese territory near the mouth of the river Tagus. It means “Land of Serpents”. The river Tagus empties into the Atlantic Ocean near Lisbon and Parede.

Remarks. The type series of 2014 was collected by sweeping an aerial net against or just above the rocks and the intertidal pools (fig. 4) on a rocky shore strictly adjacent to the town of Parede. In all probability, the three specimens collected by Fonseca in 1961 were also netted in the same habitat or nearby. Canace ophiusae sp. nov. shares the same rocky habitat with the common C. nasica , the latter collected in dozens of specimens of both sexes. The male specimens of the new species exhibit widely exposed external terminalia, so that it was particularly easy to assign them to the new taxon, maintaining the abdomen in situ without need to dissect the postabdominal sclerites (except for one male, whose abdomen was dissected and the terminalia illustrated herein).

Externally this species is similar to C. actites , but differs in the number of setae on the mesofrons ( C. actites bears only 1 pair of large proclinate setae), which are, moreover, of the same length and strength. In addition, the new species exhibits a much more subrectangular, sharp-cornered surstylus than Mathis’ species, and the fingerlike ventral lobe is displaced at the posteroventral corner of the surstylus (in C. actites this process is otherwise placed at the anteroventral corner of the surstylus). Furthermore, the ventral lobes are quite symmetrical in posterior view, whereas the apices of these processes are distinctly asymmetrical in C. actites (see Munari, 2014, fig. 3). Despite these substantial differences, the two species appear to be closely related, and we strongly presume that they share a recent common ancestor.

Figures

FIGURES 1 – 3. Canace ophiusae sp. nov.. 1: head in oblique anterodorsolateral view. Scale bar = 0.3 mm. 2: male terminalia in lateral view. 3: ditto, posterior view. Scale bar = 0.1 mm.

FIGURE 4. Two images of the intertidal habitat where the holotype and most of the paratypes were collected (specimens caught in 2014) (original photographs by J. M. Almeida).