Minettia aenigmatica, Ebejer, 2019

Ebejer, Martin J., 2019, Taxonomic notes on West Palaearctic species of Lauxania Latreille, Sapromyza Fallén, Calliopum Strand and Minettia Robineau-Desvoidy, with a description of a new species of Minettia (Diptera, Acalyptrata: Lauxaniidae) from Morocco, Zootaxa 4543 (1), pp. 37-51 : 46-50

Minettia aenigmatica sp. n.

( Figs 34–40, 42, 43 )

Diagnosis. A yellow species with black setae and setulae, two dorsal preapical setae on the mid tibia and dark spots on anterior and posterior face at extreme apex of hind femur; the abdominal tergites have brown patches laterally; the female has no exceptionally long marginal setae on any tergite; both sexes usually have pale infuscation on the crossveins and along the apices of the costal, radial and medial veins of the wing.

Description. Male: habitus ( Fig. 34 ). Head: yellow; frons dull with yellow to pale brown pollinosity; dark brown spot between bases of antennae and a paler spot between antenna and eye margin ( Fig. 35 ); height of gena about 2/5 that of eye; antenna with scape and pedical yellow, postpedicel pale brown, arista long plumose and brown; palpus black and with rather long black setae; head setulae and setae well-developed, black and typical of the genus: 2 reclinate orbitals, very long ocellars, 2–3 pairs of ocellar setulae behind these and well-developed postocellars and medial and lateral verticals.

Thorax: ( Fig. 37 ) entirely yellow; chaetotaxy: 1 postpronotal with several setlae around its base, 0+3 dorsocentrals, 1 presutural, 2 notopleurals, 1 supraalar, 1 intraalar, 2 postalar, acrostichals in 6 somewhat irregular rows, prescutellars strong, a little longer than scutellum; scutellum with 2 pairs of marginals; 1 strong anepisternal with several scattered setulae of variable length, 2 katepisternals with several short fine scattered setulae.

Wing: ( Fig. 34 ) slightly tinged greyish brown with more distinct, but still light infuscation around crossveins and at apex.

Legs: yellow except for small brown spot on anterior and posterior aspect of extreme apex of hind femur ( Fig. 36 ); fore femur with a row of long anterodorsal and posterdorsal setae; basitarsomeres of all legs with dense brush of slightly spinose setulae; mid femur with anterior row of setae over apical half, mid tibia with 2 dorsal preapical setae.

Abdomen: ( Fig. 38 ): yellow with large brown patches laterally on tegites 3–6, occupying a little less than half length of tergite dorsally and whole length laterally and ventrally; marginal setae about 2/3 length of respective tergite.

Terminalia: ( Figs 40, 42, 43 ): epandrium and surstylus yellow, latter with blunt rectangular tooth at apex, left postgonite with rounded apex and with seta at middle, right postgonite pointed apically and with seta originating at middle.

Female: as male except for secondary sexual characters; marginal setae of tergites ( Fig. 39 ) as in male, ie without any special development; basitarsomeres of all legs with ventral brush less developed than in male.

Body length: male and female 5 mm, Wing length: male and female 4.5 mm.

Variation. a light brown darkening across middle of frons can be present in some specimens (as in many species of Minettia ); brown spots between antenna and eye margin can be less marked, extent of abdominal brown marking variable (in one somewhat teneral specimen these markings are hardly developed); wing markings can also be less distinct in some specimens.

Etymology: from the Latin word aenigma = puzzle or confusing, because the wing pattern coupled with the unusual abdominal colour pattern was initially puzzling to place this species among its congeners.

Material. Holotype, male, Morocco, Tanger, Perdicaris Park, 35°47'27''N 05°51'13''W, 223 m asl, 16.v.2015, KK & A. Adghir, deposited in the Natural History Museum, London, UK, registration number: 0 12809094 . Paratypes, 2♂♂, 1♀, same data ( NHMUK) registration numbers 012809095–012809097 ; 7♂♂, 3♀♀, same data ( PKK) and 4♂♂, 1♀, same data ( PMJE) ; 3♀♀, High Atlas, Jebel Ayachi, Mikdane, stream, 5.viii.1963, Oxford University Expedition, A.C. Pont ( NHMUK) registration numbers 012809098–012809100 ; 1♀, Tétouan, Khmis Anjra, Oued Khmis, 35°39'51'' 05°30'29'', 61 m asl, 16.ix.2012, riparian vegetation, KK ( ISR). The specimens from Tanger, Perdicaris Park, had been stored in alcohol and are damaged to a variable degree. Those from samples dated 2012 and 2015 that are deposited in NHMUK, ISR and PMJE , were extracted from alcohol and passed through ethyl acetate before being dry mounted.

Similar species. The general appearance of the new species, mainly because of its abdominal colouration, is similar to pale forms of Minettia inusta (Meigen, 1826) , a species found in all of Europe including Iberia. These pale forms of M. inusta look similar to the new species since they have the dark spots on the face between the antennae and near the eye margin, dark spots apically on the hind femur and dark pattern on the abdomen. However, M. inusta usually has only one preapical seta on the mid tibia (specimens with a short additional seta occur in about 40% of cases), 1+3 dorsocentral setae and the dark colouration in the subcostal and first radial cell always present (always absent in aenigmatica ). The number of dorsocentral setae and the single apical seta on the mid tibia excludes M. inusta from the punctiventris group even though it shares the other characters. This division into species groups is artificial and it is not clear on which criteria should more weight be given to one or other of the characters noted above. The key given below separates the new species from its congeners in the punctiventris group. The terminalia of M. inusta is illustrated for comparison with the new species ( Figs 41, 44 ) because these two species can appear the most similar. Note the difference in size of the cerci and surstyli relative to the epandrium in the respective species; the shape of the postgonites and the origin of their setae. From the related species in the punctiventris group, M. aenigmatica is easly distinguished by the colour pattern on the abdomen, the wing markings and details of the male terminalia. For illustrations of the terminalia of other species of the punctiventris group the reader is referred to Papp (1981). In females, M. aenigmatica and M. inusta all marginal setae on the tergites are shorter than their respective tergite, wheres in all the other species of the punctiventris group the marginal setae on tergite 5 are well-developed and longer than the tergite.

Distribution. Morocco.

Papp (1981) gave a key to the species known at the time and illustrated the male terminalia of most of them.

The key is adapted and modified here to take into account the proposed synonymies and to include the new species.

1 Palpus completely yellow, tergites 5 and 6 with a black spot laterally............................ punctiventris Rondani

- Palpus for the most part or completely black, tergites with spots or brown marks.................................... 2

2 Wing with light greyish brown infuscation around crossveins and at apex (in most specimens); abdomen usually with large diffuse brown marks laterally on last 3–6 tergites and no discreet dark spots in either males or females...... aenigmatica sp. n.

- Both sexes with entirely clear wings and yellow abdomen apart from the discreet lateral dark spots................................................................................................. suillorum (Robineau-Desvoidy) ............................................................................... syn. tinctiventris (Rondani) .................................................................................... syn. muricata Becker. ............................................................................... syn. subtinctiventris Papp

Figures

FIGURES 34–36. Minettia aenigmatica sp. n. 34) holotype, male habitus, 35) male paratype, face; 36) same, apex of hind femur.

FIGURES 37–39. Minettia aenigmatica sp. n. paratypes, 37) male thorax, dorsal, 38) male abdomen, dorsal, 39) female abdomen, dorsal.

FIGURES 40–44. Male terminalia, 40) Minettia aenigmatica sp. n. lateral, 41) M. inusta, (Porto, Portugal) lateral, 42) M. aenigmatica, postgonites ventral, 43) same, surstyli ventral, 44) M. inusta, postgonites ventral. Abbreviations: ep—epandrium, cer—cercus, sur—surstylus.