Limnophora croatica, Pont & Ivković, 2013

Pont, Adrian C. & Ivković, Marija, 2013, The hunter-flies of Croatia (Diptera: Muscidae: genus Limnophora Robineau-Desvoidy), Journal of Natural History 47 (15 - 16), pp. 1069-1082 : 1074-1081

Limnophora croatica sp. nov. ♂ ♀

( Figures 1A , 2 )

Diagnosis

Limnophora croatica sp. nov. can be recognized in both sexes by the brown to dark brown pruinosity of the fronto-orbital plate together with the long fine posteroventral and ventral apical setae on fore tibia, both setae being longer than the tibial diameter. Other characters can be found in the key to Croatian Limnophora above and in the key to Mediterranean species of the Limnophora riparia -group that follows this description.

Male ( Figures 1A , 2 )

Head. Ground-colour black. Eye bare. Frons broad, at middle 0.36 of head-width at this point, more or less parallel-sided from vertex to lunula. Ocellar strong, slightly shorter than the inner vertical; outer vertical hardly distinct from the adjacent postocular setulae. Fronto-orbital plate wholly dark brown pruinose. Parafacial brown pruinose, without trace of silvery-white pruinosity. Frontal triangle indistinct, brown dusted, only visible from certain angles and reaching a little over halfway from anterior ocellus to lunula. Frontal vitta dark, matt, brown when viewed from below. Face light grey pruinose, occiput silvery-white, brown above; gena silvery-white pruinose, when viewed from below light grey with an oval silvery patch below lowest eye margin. At middle of frons, a fronto-orbital plate 0.15 width of frontal vitta. Three or four pairs of inclinate frontal setae, with a few interspersed setulae, and two pairs of reclinate orbital setae, with several short setulae outside them on fronto-orbital plate. Antenna black; postpedicel three times as long as wide and falling short of mouth-margin by almost its own width, smoothly rounded at tip. Arista short-pubescent, the longest individual hairs hardly as long as basal width. Parafacial at middle almost as wide as width of postpedicel, bare. In lateral view, facial edge in front of level of profrons. Facial ridge with several short setulae above vibrissa. Depth below lowest eye-margin just over half length of postpedicel. Genal setae fine. Palpus black, slender. Prementum of proboscis glossy, black.

Thorax ( Figure 1A ). Ground-colour black. Viewed from above, scutum matt dark brown with paler dusted areas as follows: a whitish-grey band running along neck in front of anterior presutural dorsocentral, extending over postpronotal lobe and notopleuron; post-alar callus whitish-grey; with traces of grey dust here and there along the dorsocentral lines, especially conspicuous in front of suture where it is sometimes more brown, extending laterally to notopleuron. Pleura whitish-grey dusted. Prothoracic spiracle whitish. Scutellum, viewed from behind, grey dusted on median third, dark brown dusted laterally. Acrostichals 0 + 1, the presutural setulae in two rows. Dorsocentrals 2 + 4 (2 + 3 on one side in holotype and in two paratypes). Second post-sutural intra-alar seta weak to absent. Proepimeral seta with three or four additional short setulae. Katepisternals 1 + 2, the lower one shorter than the upper two. Proepisternal depression, notopleuron (except for setae) and meron bare. Scutellum uniformly setulose on disc, with a setula outside the apical pair directed backwards and downwards; lateral margins and ventral surface bare.

Legs. Black; coxae and femora whitish-grey, almost bluish, dusted. Fore femur with a complete row of uniform posteroventral setae. Fore tibia without submedian setae; apical posteroventral seta strong, much longer than tibial depth, and with an almost equally long ventral apical seta. Fore tarsus with four or five fine erect posteroventral hairs on tarsomere 1, and one such hair at the tip of tarsomeres 2–4. Mid femur without anteroventral setae, with three or four posteroventral setae in basal quarter, equal to femoral depth; with several anterior setae in basal half; no anterior and two posterior preapical setae. Mid tibia with one posterior seta. Hind femur without ventral setae except for three to five, rarely more, anteroventral setae in apical half. Hind tibia with one anterodorsal and one anteroventral seta; one dorsal preapical seta, anterodorsal preapical seta absent.

Wing. Long and narrow, slightly smoky. Basicosta and tegula black. Costal spine inconspicuous. Veins bare except for costa and a few setulae on and slightly beyond the node at the base of vein R4 + 5. Cross-vein r-m below or slightly beyond the point where vein R1 enters costa. Cross-vein dm-cu weakly sinuous to almost straight. Veins R4 + 5 and M1 parallel at wing-margin. Calypters white, margins creamy. Haltere yellow.

Abdomen. Ground-colour black. With light grey dust on sides and ventral surface of abdomen, including sternites, syntergosternum and epandrium, and with dark brown to black markings as follows: syntergite 1 + 2 and tergites 3 and 4 each with a pair of large, bold, well-defined, subquadrate spots, reaching from fore-margin to hind-margin and extending to lateral edge of each tergite, narrowly separated medially by dust; tergite 5 with a less well defined, median, triangular brown patch, also reaching from fore-margin to hind-margin. Tergites without strong setae, with a few lateral marginals on tergite 4, and some lateral discals and a marginal row on tergite 5. Sternite 1 bare. Sternite 5 as Figure 2A .

Terminalia ( Figure 2B, C ).

Measurements. Length of body, 4.0–4.5 mm. Length of wing, 3.5–4.0 mm.

Female

Differs from the male as follows:

Head. Frons at level of anterior ocellus 0.44 of head-width at this point, broadening slightly from vertex to lunula. Fronto-orbital plate dark brown pruinose, becoming silvery-white or sometimes more yellow below; parafacial silvery-white, like the gena. Frontal triangle distinct, brownish-grey, almost reaching lunula. At middle of frons a fronto-orbital plate 0.20 width of frontal vitta. Depth below lowest eye-margin 0.75 of length of postpedicel.

Thorax. Scutum when viewed from behind with a pair of weak to conspicuous whitishgrey vittae running through the dorsocentral setae and confluent behind with the whitish-grey postalar callus, and with a pair of less distinct whitish-grey patches between intra-alar and supra-alar setae. Scutellum with the dark areas reduced and confined to the area of the sub-basal and apical setae.

Legs. Fore tarsomere 1 with only one or two posteroventral hairs, the other tarsomeres without longer hairs. Mid femur with the posteroventral setae present but weaker. Hind femur with three or four anteroventrals.

Abdomen. Markings as in male, but spots on syntergite 1 + 2 smaller and the median patch on tergite 5 reduced to a weak or developed median vitta. Setae weak.

Ovipositor. Not examined.

Measurements. Length of body, 5.0–5.5 mm. Length of wing, 4.5–5.0 mm.

Type material

Holotype. ♂, Croatia: Izvor Krupe , 6.vii.2011, M. Ivković (in BMNH).

Paratypes. 16♂ 19♀. Croatia : 2♂ 3♀, same data as holotype (1♂ 2♀ in BMNH, 1♂ 1♀ in OUMNH); Roški Slap , Krka River, 25.v.2011 , M. Ivković, 1♀ (in BMNH); the same, 28.iv.2011 , M. Ivković, 8♂ 3♀ (4♂ 2♀ in BMNH, 4♂ 1♀ in OUMNH)); spring of Krka River , 25.v.2011 , M. Ivković, 1♂ 1♀ (in BMNH); spring of Krupa River , 30.iii.2011 , M. Ivković, 1♀ (in OUMNH); the same, 29.iv.2011 , M. Ivković, 2♀ (in BMNH and OUMNH); the same, 26.v.2011 , M. Ivković, 1♂ 4♀ (2♀ in BMNH, 1♂ 2♀ in OUMNH); spring of River Kosovčica , 31.viii.2011 , 1♀ (in OUMNH); spring of River Ruda , 22.vi.2005 , 1♂ (in OUMNH); Plitvice Lakes, spring of Crna rijeka, P3, em. 5.v.2007 , M. Ivković, 1♂ (in BMNH); Korana village , P6, em. 29.vi.2007 , M. Ivković, 1♀ ( OUMNH); Plitvice Lakes, tufa barrier Labudovac, P 1, ix.2009 , M. Ivković, 1♀ ( ZMUC); Plitvice stream, P6, em. v.2008 , M. Ivković, 1♂ ( OUMNH); spring of River Bijela , P5, em. v.2009 , M. Ivković, 1♀ ( BMNH); the same, em. viii.2009 , M. Ivković, 1♂ ( ZMUC) .

Etymology

The specific name is an adjective formed from the country name “ Croatia ”. Its case is nominative singular, and it agrees with the feminine noun Limnophora .

Distribution

So far known only from Croatia, but probably more widespread in the Balkan Peninsula.

Phenology

The adults start to emerge at the end of March at the spring sites in the Mediterranean area, and the flight period extends throughout the summer months.

Ecology

Limnophora croatica was caught mostly at spring sites where the temperature of the water ranged from 7.5 ◦ C (spring of Crna rijeka) to 10.2 ◦ C (spring of Krupa River, Fig. 1C ), depending on the situation of the individual springs. Adults also occurred further downstream alongside rivers (Roški Slap, Krka River). They were collected mostly while sitting on rocks or algal masses, or from the vegetation adjacent to the water habitat. On one occasion, part of the courtship process was observed, when a male came face-to-face with a female and signalled to her with a movement of his left wing.

Relationships

Limnophora croatica sp. nov. is closest to Limnophora patellifera (Villeneuve, 1911) because of the long posteroventral and ventral apical setae on fore tibia, but differs by the structure of the male fore tarsomeres and by the scutal pattern. It can be distinguished from related species by the following key.

Key to the Mediterranean species of the Limnophora riparia group

(sg. Calliophrys Kowarz, 1893 )

Species of the Limnophora riparia -group can be recognized by the dichoptic head of the male; the frons, when the head is viewed in profile, flat and forming almost a rightangle with the face; and the gena below eye broad and equal to at least half the length of the postpedicel.

1. Only one pair of reclinate orbital setae. Sternite 1 with several setulae. 2 + 3 dorsocentrals...................................... bipunctata (Stein) Two pairs of reclinate orbital setae. Sternite 1 bare. 2 + 4 dorsocentrals, but individually and exceptionally 2 + 3...................................... 2

2. Fronto- orbital plate velvety-black....................... pulchriceps (Loew) Fronto-orbital plate silvery-white or brown pruinose, never velvety-black... 3

3. Frons widening gradually from vertex to lunula. Frontal triangle silvery-white pruinose and conspicuous, reaching lunula. Vibrissal area black, contrasting with the silvery-white lower parafacial and gena............. riparia (Fallén) Frons parallel-sided or narrowing slightly from vertex to lunula. Frontal triangle brown pruinose and very inconspicuous, not always reaching lunula. Vibrissal area silvery-white pruinose, concolorous with lower parafacial and gena.................................................................... 4

4. Hind tibia without an anteroventral seta. Fore tibia with the apical ventral seta absent and the apical posteroventral seta minute, much shorter than tibial width. ♂: mid femur with four or five anteroventral setae in basal half, longer than femoral depth, and a row of longer posteroventrals on all but apical quarter that decrease in length apicad........................................................................... femoriseta Pont, Vikhrev and Werner Hind tibia with an anteroventral seta. Fore tibia with the apical posteroventral seta as long as or longer than tibial width. ♂: mid femur without anteroventral setae, and with only a few posteroventrals that are confined to basal half or less..................................................................... 5

5. ♂♂ ..................................................................... 6 ♀♀ ...................................................................... 9

6. Fore tarsus very elongated, almost or quite twice as long as fore tibia, tarsomeres 1–4 compressed and thin, tarsomere 5 flattened and expanded plate-like........................................... patellifera (Villeneuve) Fore tarsus normal in length and unmodified in structure.................. 7

7. Fore tibia with the apical ventral and posteroventral setae much longer than tibial width. Gena with an oval silvery patch below lowest eye margin. Scutellum with a broad light grey dusted median vitta, the dark areas confined to the sides................................................ croatica sp. nov. Fore tibia with the apical ventral seta absent and the apical posteroventral seta at most as long as tibial width. Gena without a differentiated silvery patch below lowest eye margin. Scutellum entirely dark dusted, with little or no paler dust on disc............................................................. 8

8. Postpedicel enlarged throughout its length towards apex, much broader at tip than at base and rather truncated. Parafacial dull grey, tinged with brownish above. Fronto-orbital plate entirely matt brown pruinose........................................................................... caesia (Villeneuve) Postpedicel of equal width throughout, narrow and rounded at tip. Parafacial silvery-white pruinose. Fronto-orbital plate dark brown but silvery-white below..................................................... exuta (Kowarz)

9. Scutellum mostly grey dusted, with a pair of small black spots that are confined around the sub-basal setae. (Fore tibia with well-developed apical ventral and posteroventral setae that are longer than the tibial width at this point).................................................... patellifera (Villeneuve) Scutellum with the dark patches much more extensive, the grey dusted area confined to a median vitta, but if more extensively grey dusted then fore tibia with the apical ventral seta absent....................................... 10

10. Fore tibia with the apical ventral and posteroventral setae fine and about 1.5 times as long as tibial width. (Hind femur with three or four anteroventral setae in apical third)....................................... croatica sp. nov. Fore tibia with the apical ventral seta absent and the apical posteroventral seta as long as tibial width.................................................. 11

11. Hind femur with one or two anteroventral setae just before apex.................................................................... caesia (Villeneuve) Hind femur with five or six anteroventral setae in apical half........................................................................... exuta (Kowarz)

Figures

Figure 1. (A) Limnophora croatica sp. nov., male habitus, dorsal view (holotype); (B) spring of Bijela rijeka, emergence trap; (C) Izvor Krupe, the type locality of Limnophora croatica sp. nov.

Figure 2. Limnophora croatica sp. nov. (A) Male sternite 5; (B) male hypopygium, lateral view; (C) male cercal plate, dorsal view. Paratype male from Croatia, Izvor Krupe, 6 July 2011 (M. Ivković). Scale bar: 0.1 mm.