Micropsectra appendica, Stur & Ekrem, 2006

Stur, Elisabeth & Ekrem, Torbjørn, 2006, A revision of West Palaearctic species of the Micropsectra atrofasciata species group (Diptera: Chironomidae), Zoological Journal of the Linnean Society 146 (4), pp. 165-225 : 176-178

MICROPSECTRA APPENDICA SP. NOV.

Micropsectra appendiculata . ( Dittmar, 1955; Säwedal, 1982b) nomen nudum.

Holotype £ ( ZMBN no. 409; To 133) Norway, Hordaland, Bergen, Espeland at marin research station, sweep net, 07.vi.2003, E. Stur & T. Ekrem. 46 paratypes: 3££ ( ZMBN) as holotype; 1 P£ & 1 Pex ( ZMBN) Norway, Hordaland, Vaksdal, Eksetjørni, 20.vi.1986, Ø. A. Schnell; 5££ ( VM) Norway, Møre og Romsdal, Rauma, Fiva, MT, 29.vii.1992, 9.viii.1992, 12.v.1995, 15.viii.1995, 20.ix.1995, K. Aagaard & O. Hanssen; 10££ ( VM) Norway, Oppland, Dovre, Atnaelv, Dørålseter, MT, 2.vii.1986, 8.vii.1986, K. Aagaard & O. Hanssen; 1£ ( VM) Norway, Hedmark, Storelvdal, Atnaelv, Solbakken, MT, 16.viii.1986, K. Aagaard & O. Hanssen; 1£ as previous, except at Storbekken, 29.viii.1988. Germany ( ZSM): 3££, Nordrhein-Westfalen, Sauerland, Aabach brooklet S Albaum spring region, c. 550 m a.s.l., c. 1950, H. Dittmar; 2££ & 1 Pex, Hessen, Rhön mountains E of Fulda, helocrene on Wasserkuppe mountain , 870 m a.s.l., 4.ix.1953, 20.x.1953, 28.x.1963, E. J. Fittkau; 2££ & 3 Pex , Baden-Württemberg, Schwarzwald , Ursee , 837 m a.s.l., 12.v.1954, 01.iv.1955, W. Wülker; 2££, 4 Pex , Baden-Württemberg, Schwarzwald , Löschteich at Falkau , c. 900 m a.s.l., near Hydrobiol. Station , sweep net, 15.iv.1955, W. Wülker; 1 P£ & 1£ Baden-Württemberg, Schwarzwald , Windgfällweiher at Altglashütten , 966 m a.s.l., at outlet, 23.iv.1955, W. Wülker; 1£, Baden-Württemberg, Schwarzwald , 30.vi.1950, prob. Elster. 2££ & 1 P$ ( ZSM) Finland, northern province Lapponia Kemensis , Sondankylä , Kotaoja river , 14.vi.1959, 21.vi.1959, 25.vi.1959, M. Hirvenoja. 1£ ( WG) Poland, Rwietokrzyskie Mts. , Zagnansk-Jaworze , ex cult., 26.xi.1977, J. Sicinski.

Etymology

The species epithet ‘appendica’ refers to the comparatively large median volsella in the male hypopygium, and is to be used as an adjective.

Diagnostic characters

Micropsectra appendica can be separated from other species in the atrofasciata group by the following combination of characters. Adult male with pulvilli about half length of claws; anal point well developed, comparatively long, apically rounded, knob between crests present; superior volsella with small field of microtrichia on stem; digitus short and thin or triangular; median volsella strong, club-shaped, with stem almost reaching apex of inferior volsella, numerous spoonshaped lamellae covering distal third dorsally. Pupa with short cephalic tubercles; relatively short thoracic horn with long chaetae on distal 2/3; field of fine granulation anteriorly on evenly pigmented thorax; strong spines in patches on tergite III and on tergite IV (in the longitudinal, lateral extensions); spinules and points in patches on tergite V; patches on tergites IV–VI of equal form and size; microtrichia in between spine patches on tergite III; dorsolateral comb of segment VIII narrow, with 5 marginal teeth, median tooth longer than remaining teeth.

Description

Adult male. Measurements and ratios in Table 1.

Coloration. Body and legs greenish or brownish with dark brown pedicels, vittae, postnotum, median anepisternum II, preepisternum and epimeron II; scutellum and halteres light brown.

Head. Antenna with 13 flagellomeres. Frontal tubercles present (10–14 µm); temporal setae in 1 row; palpomere 3 with 2 sensilla clavata in subapical pit.

Wing. Subcosta and media bare, brachiolum with 2–3 setae, squama bare.

Legs. Pulvilli present, almost half as long as claws. Fore tibia with small scale, 18 µm long spur; mid and hind tibial combs c. 18 µm long; mid ta 1 with 5 sensilla chaetica.

Hypopygium ( Fig. 5A–C ). Anal tergite with separate, posteriorly directed anal tergite bands; 4–10, 7 median tergite setae placed on an elevated hump anterior to anal point base; 8–14, 11 ventral apical setae. Anal point comparatively long, with high, slightly curved anal crests, apex rounded or slightly concave; knob between crests large; relatively large microtrichia-free area at base, except lateral, of anal point. Superior volsella roundish with 6–10, 8 dorsal and 2–4, 3 median setae on setiger, 1 strong seta on stem; a small field of microtrichia dorsally on stem and a large field ventrally on setiger. Digitus small, thin or triangular, not reaching margin of superior volsella. Median volsella club-shaped, comparatively long and thick, with setiform and spoon-shaped lamellae; spoon-shaped lamellae on distal 1/3; stem almost reaching apex of inferior volsella. Inferior volsella without dorsoapical and dorsomedian swellings, bearing numerous distal setae. Inner margin of gonocoxite with 3–4 strong setae.

Pupa. Coloration: pupal exuviae brownish with dark brown apodemes; cephalothorax, TVIII and anal lobe darker brown. Measurements in Table 2.

Cephalothorax ( Fig. 5D, E ). Cephalic tubercle present, small, conical; pedicel sheath tubercle weakly developed. Thoracic horn fairly short, with numerous long chaetae on distal 2/3; precorneals arranged in triangular pattern, the two anteriormost setae situated closer to each other than to the third; 2 lateral antepronotals (1 seta, 1 sensillum basiconicum); 2 pairs of dorsocentrals, anterior pair often placed further from each other than posterior pair, posterior pair with 1 thick and 1 thin seta. Coarse granulation dorsally on anterior half of thorax. Prealar tubercle weak; nose of wing sheath weak.

Abdomen ( Fig. 5F, G ). TII almost covered by shagreen except for one mediolateral and one posteromedian oval patch; pedes spurii B on segment II obvious; hook row about half as long as segment width. Spines of TIII in large, patches at slight angle to mid-line, shagreen extensively distributed lateral and anterior to spine patches as well as in between. Patches on TIV consisting of spinules in anterior, oval patches with spines in longitudinal, lateral extensions; shagreen present lateral to the anterior patches. Patches on TV similar to those on TIV in shape, and about equally long, but consisting of spinules and points only. Patches on TVI similar to those on TIV and TV in shape, and about equally long, but consisting of shagreen only. TVII and TVIII with weak anterior patches of shagreen. Segment I with 3 D, 1 V and 2 L setae; segment II with 3 D, 4 V, 3 L; segment III with 5 D, 4 V, 3 L; segment IV with 5 D, 4 V, 1 L, 2 lateral taeniae; segment V with 5 D, 4 V, 3 lateral taeniae; segment VI with 5 D, 4 V, 4 lateral taeniae; segment VII with 5 D, 4 V, 4 lateral taeniae; segment VIII with 1 dorsal taenia, 1 ventral taenia, 5 lateral taeniae; anal tergite with 1 dorsal taenia. Two pairs of small sensorial setae medially on TII–VII; 1 pair of O-setae present anteriorly on segments II–VII. Anal lobe with lateral margins abruptly curved posteriorly, fringe with about 600–700 µm long taeniae in 1 row. Posterolateral comb of segment VIII ( Fig. 5H ) narrow, with median tooth usually longer than remaining teeth.

Larva unknown.

Remarks

Micropsectra appendica exhibits quite large variation in superior volsella setation, and the number of median setae on the setiger is variable even in a single specimen. The species has been mentioned in the literature ( Dittmar, 1955; Säwedal, 1982b), but was never described formally, although Lars Brundin apparently planned to do so about 40 years ago. It has been collected near several different types of water bodies (ponds, rivers, streams, brooks and springs), and apparently has a fairly wide geographical distribution. DNA has been extracted from the holotype and one paratype and will be used also in future molecular systematic analyses.

The species most similar to M. appendica appears to be M. tusimalemea Sasa & Suzuki, 1999 . We have examined the holotype and six paratypes of the Japanese species and have found that M. appendica can be separated by having an apically broad, club-shaped median volsella, smaller and more numerous spoonshaped lamellae of the median volsella, and a smooth outer margin of the inferior volsella without the obvious hump seen in M. tusimalemea ( Sasa & Suzuki, 1999: fig. 18f).

Figures

Figure 5. Micropsectra appendica sp. nov. A, hypopygium. B, variation in superior volsella. C, superior, median and inferior volsellae. D, pupal thorax. E, pupal frontal apotome. F, pupal abdominal segments II–VI, dorsal. G, pupal abdominal segments VIII–IX. H, variation in posterolateral comb of pupal segment VIII.