Micropsectra uva, Giłka, Wojciech, Zakrzewska, Marta, Baranov, Viktor A. & Dominiak, Patrycja, 2013

Giłka, Wojciech, Zakrzewska, Marta, Baranov, Viktor A. & Dominiak, Patrycja, 2013, Diagnostic clues for identification of selected species of the Micropsectra atrofasciata group, with description of M. uva sp. nov. from Croatia (Diptera: Chironomidae: Tanytarsini), Zootaxa 3702 (3), pp. 288-294 : 289-292

Micropsectra uva sp. nov.

Type material. Holotype, male (in DIZP): CROATIA, Plitvice Lakes National Park, springs of Bijela Rijeka (44º50’N 15º33’E, 720 m a.s.l.), 25 July 2007, pyramid emergence trap, leg. M. Ivković. Paratypes: 6 males (4 in DIZP, 2 in MSIZ), same data as holotype.

Derivation of the name. From Latin, meaning 'bunch of fruits', in reference to the shape of the hypopygial median volsella; noun in apposition.

Diagnosis. Stem of median volsella short, straight or slightly curved at tip posterolaterally turned, blunt apex reaching midpoint of superior volsella and half length of inferior volsella at most; spoon-shaped lamellae arranged in 3–4 rows, placed on distal half of stem and posteromedially directed; stem/spoon-shaped lamellae length ratio c. 2.5. Inferior volsella slightly curved at base, narrowest in mid length, with swollen and posteromedially turned distal half, transverse protrusion very slight if present.

Description. Adult male (n = 7, unless otherwise stated)

Colouration. Eyes and tibial combs black, other parts of the body yellowish green, with antenna, scutal stripes and sternum slightly darker.

Head. Antenna with 13 flagellomeres, plume well developed, AR 0.60–0.70 (0.64, n = 3). Frontal tubercles absent. Length of palpomeres 2–5 (Μm): 48–64 (56, n = 3), 155–181 (164, n = 3), 128–155 (137, n = 3), 227–271 (244, n = 3). Clypeus with 10–18 (13) setae.

Thoracic chaetotaxy. Ac 20–25, reaching antepronotum; Dc 8–10; Pa 2–3; Scts 7–8 in row.

Wing. Slightly variable in shape as shown in Figure 1 . Length (arculus–tip) 1.99–2.15 mm (2.07 mm). Sc, R2+3, M, short proximal part of M1+2, RM, 1/3 proximal section of Cu bare, remaining veins with macrotrichia; membrane except basal part covered with macrotrichia. R2+3 weak. FCu placed under RM-R connection. VR Cu 1.09–1.14 (1.12, n = 2). Veins ending as follows (in order from base to tip): An (under FCu), Sc, Cu1, R1, R2+3, M3+4, R4+5, M1+2. Anal lobe reduced.

Legs. Fore tibia with straight, c. 10–20 Μm long spur. Combs of mid and hind tibiae contiguous, placed on 50– 65% circumference of tibial apices, each comb with single somewhat longer spur-like tooth. Basitarsus of mid leg bearing 1–3 hook-shaped sensilla chaetica. For lengths of leg segments and leg ratios see Table 1 .

Hypopygium ( Fig. 2 , 3 D). Anal tergite with bands of V-type, fused at elevated hump at base of anal point, bearing 3–4 median tergite setae, lateral teeth and basilateral processes well developed. Anal point wide at base, with long crests separated distally by large knob, apex blunt, subrectangular, microtrichia-free area surrounding base of anal point extensive. Strong Micropsectra -seta sensu Säwedal (1982) placed on prominent conical tubercle at base of superior volsella. Superior volsella round, bearing 2–3 setae on anteromedian margin (proximal seta weaker) and 6–9 dorsal setae. Digitus moderately long, almost reaching margin of superior volsella, apically blunt or acute. Stem of median volsella short, c. 45–50 Μm, straight or slightly curved at tip posterolaterally turned, blunt apex reaching midpoint of superior volsella and half length of inferior volsella at most; c. 20 spoon-shaped lamellae arranged in 3–4 rows, placed on distal half of stem, posteromedially directed; stem/spoon-shaped lamellae length ratio c. 2.5. Inferior volsella with slight knee-like curve at base, narrowest in mid length, with swollen and posteromedially turned distal half, transverse protrusion usually absent or very slight. Gonostylus c. 145–170 Μm long, broadest near mid-length, tapering to rounded apex.

Micropsectra atrofasciata group; compiled from Stur & Ekrem (2006), Rossaro et al. (2009), Rossaro (pers. comm.), material

presently examined.

character/species M. pallidula M. schrankelae M. sofiae M. uva Fig. 3 A Fig. 3 B Fig. 3 C Fig. 3 D

Discussion. We compared Micropsectra uva with three species of the Micropsectra atrofasciata group: M. pallidula (Meigen) , M. schrankelae Stur et Ekrem and M. sofiae Stur et Ekrem , which have so far been recognized as close relatives ( Stur & Ekrem 2006, Rossaro et al. 2009). With respect to the variability known from the species compared, only a few differences in metric/meristic characters are sufficiently distinct and diagnostically significant. Among these M. pallidula has a relatively long wing, and high AR, LR ratio values, whereas M. uva is the smallest species, but has a relatively stout and long gonostylus. In contrast to rather low usefulness of most metric characters, the shape and arrangement of hypopygial volsellae are the essential characters in diagnostics of the four species compared. We present them in Figure 3 and Table 2 .

These four species dwell in similar habitats. The adult males of Micropsectra uva were collected in the spring (rheocrene) of the Bijela Rijeka. The stream, together with the Crna Rijeka, forms a common watercourse, the Matica river, a water-replenishment for the Plitvice Lakes. Water temperature in the spring of the Bijela Rijeka at an altitude of 720 m varies between 7.3–7.8ºC, has a slightly acid to weakly alkaline pH (6.9–7.8) ( Ivković et al. 2012). The two closest species compared, Micropsectra schrankelae and M. sofiae , are known from similar habitats, being associated with persistent low temperature in cold-water habitats at high elevations, mainly in springs (cf. Stur & Ekrem 2006, Rossaro et al. 2009); Micropsectra pallidula , well-known throughout Europe, inhabits springs and streams, as well as cold-water lakes and small standing water bodies.

We presume that female specimens found in the sample with males of Micropsectra uva belong to the same species. Unfortunately, due to lack of pupae and/or pharate specimens, association of the adults would be uncertain, thus the female could not be described.

Figures

FIGURE 1. Micropsectra uva sp. nov., male. Wing, showing slight variation (photographed using the Nomarski DIC).

FIGURE 2. Micropsectra uva sp. nov., male. Hypopygium.

FIGURE 3. Hypopygial median and inferior volsellae (ventral view) - diagnostic structures in male of Micropsectra uva sp. nov. (D) and three close species of the Micropsectra atrofasciata group: M. pallidula (Meigen) (A), M. schrankelae Stur et Ekrem (B), M. sofiae Stur et Ekrem (C).

Tables

TABLE 1. Lengths (Μm) of leg segments and leg ratios of male Micropsectra uva sp. nov.

	fe	ti	ta1	ta2	ta3	ta4	ta5	LR
p1	1005–1125 (1062)	715–810 (760)	1070–1225 (1121, n = 6)	550–630 (584, n = 6)	450–495 (467, n = 6)	310–380 (338, n = 6)	145–165 (153, n = 6)	1.40–1.53 (1.49, n = 6)
p2	910–995 (949, n = 5)	745–820 (782, n = 6)	455–500 (472, n = 5)	260–295 (278, n = 5)	210–240 (222, n = 5)	150–170 (157, n = 5)	95–105 (103, n = 5)	0.59–0.62 (0.61, n = 5)
p3	1100–1230 (1157, n = 6)	970–1080 (1022)	655–730 (685, n = 5)	420–465 (440, n = 5)	325–360 (343, n = 5)	205–230 (220, n = 4)	115–130 (123, n = 4)	0.66–0.69 (0.67, n = 5)

TABLE 2. Diagnostic characters for identification of Micropsectra uva sp. nov. and three morphologically close species of the

MVo stem shape	s-shaped, posteromedially turned, apex pointed	curved at base, posteriorly directed, apex pointed	straight, posteromedially directed, apex blunt or pointed	straight or slightly curved at tip posterolaterally turned, apex blunt
MVo stem/spoon-shaped lamellae length ratio and arrangement	ratio c. 5–6, lamellae on distal 1/ 4–1/3 length of stem	ratio c. 5, lamellae on distal 1/3 length of stem	ratio c. 2–4, lamellae on distal 1/3–1/2 length of stem	ratio c. 2.5, lamellae on distal 1/2 length of stem
MVo spoon-shaped lamellae direction	anteromedian	median	turned in various directions, mainly posterior and dorsal	posteromedian
MVo/SVo arrangement	MVo stem reaching well beyond posterior margin of SVo	MVo stem reaching beyond posterior margin of SVo	MVo stem sometimes reaching slightly beyond posterior margin of SVo	MVo stem never reaching posterior margin of SVo
MVo/IVo arrangement	MVo stem reaching 3/4 length of IVo	MVo stem reaching 2/ 3 length of IVo	MVo stem reaching 1/2– 4/5 length of IVo	MVo stem reaching 1/2 length of IVo at most
IVo shape	apex medially turned	straight	straight	slightly curved near base and posteromedially turned
IVo transverse protrusion	absent	slight	present	absent or slight