Tethina willistoni Melander

Mathis, Wayne N. & Marinoni, Luciane, 2012, A conspectus on the Canacidae (Diptera) of Brazil, ZooKeys 162, pp. 59-92 : 79-80

Tethina willistoni Melander Figs 15-17

Anthomyza cinerea Williston 1896: 444 [West Indies. St. Vincent. Wallilabou beach (13°15'N, 61°16'W); NT ♂ (designated by Foster and Mathis 1998: 615), USNM; preoccupied, Loew 1862].

Rhicnoessa cinerea . Czerny 1902: 256 [generic combination].

Rhicnoessa willistoni Melander 1913: 298 [new name for Anthomyza cinerea of Williston 1896, not Loew 1862]. Hendel 1934: 51 [citation]. Melander 1952: 201 209 [key, citation].

Tethina willistoni . Foster 1976b: 3 [generic combination, Neotropical catalog]. Mathis and Munari 1996: 19 [world catalog]. Foster and Mathis 1998: 611, 613, 615-618 [revision, Caribbean and Gulf of Mexico, neotype designation, figs. head and ♂ terminalia]. Munari and Mathis 2010: 65 [world catalog].

Rhicnoessa bermudaensis Melander 1952: 203 [Bermuda. Castle and Cooper Islands; LT ♂ (designated by Foster and Mathis 1998: 612), USNM]. Mathis and Foster 2007: 421 [synonymy].

Tethina bermudaensis . Vockeroth 1965: 727 [generic combination, Nearctic catalog]. Woodley and Hilburn 1994: 53-54 [citation, Bermuda]. Mathis and Munari 1996: 15 [world catalog]. Foster and Mathis 1998: 611-613 [revision, lectotype designation, Caribbean and Gulf of Mexico, fig. of ♂ terminalia].

Rhicnoessa variseta Melander 1952: 209 [United States. California. Orange: Corona del Mar; LT ♂ (designated by Foster and Mathis 1998: 616), USNM]. Foster and Mathis 1998: 615 [synonymy, lectotype designation].

Tethina variseta . Vockeroth 1965: 728 [generic combination, Nearctic catalog]. Mathis and Munari 1996: 19 [world catalog].

Tethina carioca Prado and Tavares 1966: 433 [Brazil. Rio de Janeiro: Ilha do Governador ( Galeão); HT ♂, FIOC (13356); figs. of ♂ terminalia and wing]. Foster 1976b: 2 [Neotropical catalog]. Mathis and Munari 1996: 15 [world catalog]. Foster and Mathis 1998: 615 [synonymy].

Tethina albula of authors, not Loew 1869 [misidentification]. Frey 1919: 15.

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Body length 1.65-3.00 mm; body generally whitish gray to gray, microtomentose; setae generally white to slightly off white but sometimes with all setae black. Head (Fig. 15): Gena high, greater than 0.5 eye height. Thorax: 4 irregular rows of acrostichal setulae; scutellum uniformly gray; femora mostly yellow to mostly gray; hindfemora of male similar to or only slightly more swollen than fore- and midfemora; tibiae yellow; basal 4 tarsomeres yellow, apical tarsomere brown. Abdomen: Male terminalia (Figs 16-17): Surstylus articulated with and broadly attached to epandrium, broadly spatulate/triangular in posterior view, length 2 –3× width, apex broadly rounded; medial margin bearing numerous short, stout setulae along entire length; surstylus in lateral view narrow, tapered to apical point, posterior margin almost straight; basal portion produced anteriorly as a broadly rounded lateral lobe bearing several short setulae medially; aedeagus thick, straplike.

Specimens examined from Brazil.

PARANÁ. Matinhos (N.; 25°46.4'S, 48°30.8'W; 1 m; beach/estuary), 25 Mar-9 Apr 2010, D. and W. N. Mathis (6♂; DZUP, USNM); Paranaguá (Rio Itiberê; 25°31.4'S, 48°30.3'W; 3 m), 23 Jan 2010, D. and W. N. Mathis (8♂, 1♀; DZUP, USNM).

RIO DE JANEIRO. Ilha do Governador ( Galeão; 22°47.8'S, 43°14.7'W), 11 Oct 1966, A. P. do Prado and Tavares (1♂; MZUSP).

SANTA CATARINA. Barra Velha (26°38'S, 48°40.9'W; beach), 29 Apr 2010, D. and W. N. Mathis (8♂, 1♀; DZUP, USNM).

SÃO PAULO. Ubatuba, Praia Puruba (23°21'S, 44°55.6'W; beach), 29 Mar 2010, D. and W. N. Mathis (6♂, 2♀; DZUP, USNM); Ubatuba, Praia do Estaleiro (23°20.5'S, 44°53'W; beach), 30 Mar 2010, D. and W. N. Mathis (1♂; USNM).

Distribution.

Australasian/Oceanian:Hawaii (French Frigate Shoals, Hawaii, Kahoolawe, Kauai, Lisiansky, Maui, Oahu), Midway Islands. Nearctic:Bermuda, United States (California, Connecticut, Delaware, Florida, Maryland, Massachusetts, North Carolina, South Carolina, Virginia). Neotropical: Bahamas, Belize, Brazil ( Paraná, Rio de Janeiro, Santa Catarina, São Paulo), Cuba, Curaçao, Ecuador, Mexico (Chihuahua, Tabasco), Panama, Peru, Tobago, Turks and Caicos, West Indies (Anguilla, Antigua, Barbados, Barbuda, Dominica, Dominican Republic, Grand Cayman, Grenada, Jamaica, Montserrat, Puerto Rico, St. Croix, St. Lucia, St. Vincent).

Remarks.

Some slight variation was evident in the shape of the surstyli within specimens of this species. In posterior view the surstylus varies from being shorter and more exactly triangular to being slightly longer but still triangular. Previously we considered these differences to represent separate species, Tethina bermudaensis and Tethina willistoni . After examination of many dissected specimens from Canada south through southern Brazil, we agree with Foster and Mathis (2008) that this variation is intraspecific.

The variation in setal coloration and size of Tethina willistoni is remarkable. The variation in external characters is as follows: the more robust specimens from the Carribean areas have mostly stout, black setae and often present a very “bristly” habitus (similar to Tethina spinulosa and Tethina horripilans ). Smaller, more delicate specimens have only the apical scutellar setae black with all other setae being white. Many specimens fall between these two extremes, making it virtually impossible to distinguish between Tethina willistoni and other species on the basis of external structures alone. A very similar chaetochromatic variation is also found in the Western Palearctic Tethina albosetulosa (Strobl) ( Munari and Canzoneri 1992; Munari and Vanin 2007).