Usia ignorata Becker, 1906

Gibbs, David, 2011, 2960, Zootaxa 2960, pp. 1-77 : 53-56

Usia ignorata Becker, 1906

( Fig. 8, Plate XIV)

Usia ignorata Becker, 1906: 15 [ 1906: 225].

Usia pallescens Becker, 1906: 226 . Syn. nov.

Usia sp. no. 5: Theodor, 1983: 64, Figs. 175–177.

Type material of ignorata examined. LECTOTYPE here designated: Tunisia, Gafsa, [leg. L.] Biró / 53035/ Usia ignorata Beck ♂ S. Paramonov det./ Typus / Zool. Mus. Berlin [♂ in ZMHB] . PARALECTOTYPE: Mahares, [leg. L.] Biró iii. ii.1903 / 53035/ Typus / Zool. Mus. Berlin [♂ in ZMHB] .

Type material of pallescens examined. LECTOTYPE here designated: Tunisia, Mahares, [leg. L.] Biró iii. ii.1903 / Gafsa. Tunis 53035/ pallescens Beck. Det. Becker / Typus / Zool. Mus. Berlin [♀ in ZMHB]. PARALEC- TOTYPE: Spain, Andalusia, [leg.] Staudinger/ forcipata ? Brull./9688/Coll. H. Loew/ pallescens Beck. Det. Becker / Typus / Zool. Mus. Berlin [♀ in ZMHB = pusilla / susanae Det. D.J. Gibbs ].

Other material examined. Algeria, Metlilia, Sidi Maklouf 15 April 1893, Museum Paris, Algérie, [leg.] P. Lessne 6-97 [♀ in MNHN] . Israel, Mishkor Rotem, 18 February [19]65, [leg.] M. Weichselfish / 596, 1500 / Holotype, Usia treibensis, Theodor , det. O. Theodor 1985 [♂ in TAU];18 January [19]65 / Paratype, Usia treibensis, Theodor , det. O. Theodor 1985 [2♂ in TAU]; 12 February [19]65 [♂ in TAU];14 February [19]65 [2♀ in TAU]; 17 February [19]65 [♀ in TAU]; 18 February [19]65 [♂ 3♀ in TAU]; 21 February [19]65 [♀ in TAU]; 23 February [19]65 [♂ 3♀ in TAU]; 24 February [19]65 [♂ 2♀ in TAU]; 28 February [19]65 [♂ 3♀ in TAU]; 3 March [19]65 [♀ in TAU]; 3 March [19]65 [2♂ 4♀ in TAU]; 5 March [19]65 [3♂ 2♀ in TAU]; 8 March [19]65 [♀ in TAU]; 13 March [19]65 [2♂ 2♀ in TAU]; 28 March [19]65 [♂ in TAU]; Tel. Jerucham, 19 February [19]62 [♀ in TAU] . Tunisia, Museum Paris , Gafsa, [leg] A. Weiss 1904 [2♂ 8♀ in MNHN] .

Etymology. The specific epithet derives from the Latin “ ignoratum = to not know”, but Becker (1906) does not explain why he chose this name.

Diagnosis. A small entirely black species, teneral or faded specimens often browner, especially legs. Four hind femora, especially middle pair, with long, outstanding hairs (but these can be few and easily lost), scutellum with marginal hairs longer than scutellum is long medially, mesonotum shining and relatively smooth (not matt), anepisternum almost entirely dulled by dust. Male genitalia very large and rather elongate, epandrium with short, sub-apical elongations that often enclose the cerci. Most females have penultimate sternite furnished with a distinct tuft of long, black hairs apicomedially, reliable identification relies on dissection of the terminalia.

Redescription. Measurements. Body length. 2.5–3.2mm Wing length. 2.5–3.2mm.

Male. Head. Frons relatively narrow, about a sixth to a fifth head width, at narrowest point about as wide or a little narrower than length of third antennal segment, rather shining but finely longitudinally striated with narrow, triangular grey dust spots anterolaterally. Mouth margin very narrow, shining, linear. Ocellar tubercle shining, ocelli obtuse, lateral ocelli separated from the eye by half their diameter. Longest hairs on ocellar tubercle about as long as depth of femora, longer than width across vertex at lateral ocelli. Occiput covered with grey dust obscuring ground colour, this dusting a little thinner on triangular area behind vertex. Black hairs on occiput short above, much longer below, those on ventral side of head almost as long as those on ocellar tubercle. Antennae black, relatively elongate, third segment rather variable but usually elongate, straight dorsally before sulcus, undulating PLATE XIV. Usia ignorata Becker, 1906 ; a epiphallic complex ventral, b epiphallic complex lateral, c gonocoxite ventral, d gonocoxite lateral, e epandrium dorsal, f epandrium lateral, g female genitalia ventral, h female sternite 8 ventral.

ventrally with convex base and slightly constricted subapically, about twice as long as scape and pedicel combined. A few very short dark setae on dorsum of third antennal segment immediately before apical sulcus, sensilla white in a few specimens, more usually dark brown. Proboscis black, naked, about as long as mesonotum. Palps very small, black to brown, subclavate with a tuft of apical setae as long as the palp. Thorax. Entirely black, mesonotum shining and mostly smooth to inconspicuously wrinkled with hair insertions not obvious, lightly grey-dusted on pronotum, postpronotal lobe, notopleuron and above wing base in thoracic suture. Mesonotum with long, scattered, perpendicular black hairs as long as those on ocellar tubercle, acrostichals irregularly biserial, paramedian lines bare but not readily discerned, extending back to above wing bases, laterally hairs generally distributed, lateral hairs the longest. Scutellum shining, surface no more than obscurely transversely wrinkled, disc with scattered long black hairs, hind margin with a somewhat irregular, almost uniserial, row of longer, posteriorly directed black hairs longer than scutellum is long. Pleura black to dark brown, predominantly grey-dusted, especially anepisternum which is only narrowly shining anteroventrally (variable), katepisternum more shining ventrally. Dorsal half of anepisternum with dark hairs shorter than those on notopleuron. Wing. Clear to tinged brownish, the veins brownish yellow. Anal lobe convex, slightly but distinctly narrower than anal cell. Haltere. White knob, stem slightly infuscated basally. Legs. Black to dark brown, shining but with rough texture to cuticle, with very short, adpressed black hairs, hind and especially mid-femora with long, erect black posteroventral hairs, the longest clearly longer than the depth of the femora. These long hairs seem to be very fragile and in many specimens just a few can be found on the mid-femora, or they are lacking entirely. Abdomen. Black, short with very broad tergites, surface sculpture of transverse welts at each hair insertion. Disc of tergites covered with relatively short, dense black hairs, much longer hairs laterally. Sternites grey dusted with long black hairs along apical margins. Genitalia. Large, almost as large as the remainder of the abdomen, length of epandrium clearly exceeding length of sternites. Epandrium apically clasped around the cerci with two protuberances each side, a small hooked one near the cerci, larger more rounded one set subapically. Gonocoxite basally bilobed with long erect black hairs, apically more shining and more yellow, often obscured by enclosing epandrium. Tip of epiphallus bifurcated into two pointed lobes furnished with inwardly pointing spines.

Female. Very similar to the male. The frons of the female is on average very slightly broader than in males, between a fifth and a quarter head width, hind ocellus separated from eye margin by about the diameter of that ocellus. The mouth margin is also a little broader but this is marginal. Hairs generally shorter, most conspicuously so on the disc of the tergites. Anal lobe averages wider. Apical sternite rather rectangular, parallel sided, base slightly translucent forming a brown, wrinkled patch in dry specimens, angled at distal margin of this patch forming a low transverse ridge, a shallow apical notch apparent. In most individuals the penultimate sternite is furnished with a distinct tuft of long, black hairs apicomedially, conspicuously more dense than laterally, a less obvious tuft sometimes apparent on 6 th sternite.

Discussion. This species is not obviously closely related to any other known species, perhaps with affiliations to U. echinus and U. dilsi .

Although Becker originally described this species using specimens of both sexes from Syria, Tunisia and Morocco, only two males from Tunisia seem to have survived in ZMHB. One of the lost specimens was in the HNHM and was destroyed in the 1956 uprising. A female of this species was found in the ZMHB material but it was one of the two syntypes of U. pallescens from same site and collected on the same date as the paralectotype of U. ignorata . The other syntype of U. pallescens , a female from Spain, Andalusia, is a quite clearly different species, either U. pusilla or its sibling species U. susanae , both very short-haired taxa. As the key and description provided by Becker suggests that U. pallescens is a long-haired species close to U. ignorata , the Tunisian specimen has been chosen as lectotype thus U. pallescens becomes a junior synonym of U. ignorata . The alternative option of choosing the Andalusian specimen not only would not conform to Becker’s original description, but as it is a female it cannot be certainly identified. Of the two short-haired Micrusia known from Spain, this paralectotype of U. pallescens most closely equates to U susanae . However, as the females are rather variable and there are no associated males, it would be unsafe to designate this specimen as a type.

It is difficult to believe that Becker really meant to include both of these specimens as the types of U. pallescens . They are so different that even a casual look would convince any experienced dipterist that they are not the same species. However, the localities listed in Becker (1906) do seem to conform to the data labels so it seems unlikely that a mix up has occurred after publication. Given that U. ignorata does not occur in Andalusia, and U. susanae does not occur in Tunisia, simply transposing specimen labels could not be the explanation and there is no reason to believe that either specimen is mislabelled. The error must have been Becker’s, applying determination labels incorrectly then failing to double check the specimens before extracting the data for his manuscript.

Distribution. Algeria, Israel, Egypt, Tunisia. Although widespread, localities are few and far between, clearly very local but has been found in good numbers at a few sites especially in Israel and Egypt. No Egyptian specimens have been seen, but it is clear from Efflatoun (1945: Plate XX Fig. 324) that he had this species before him. However, a single specimen from Abu Rowash sent to Theodor proved to be U. echinus (♂ in TAU), so Efflatoun had a mixed series consisting of at least two species. Thus, it is not possible to know which of the sites listed by Efflatoun (1945) refer to U. ignorata and which refer to U. echinus or other species he failed to distinguish.