Micropsectra robusta, 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 : 204-206

MICROPSECTRA ROBUSTA SP. NOV.

Holotype £ ( ZSM), Luxembourg, Oesling , W Clervaux, rheohelocrene spring no. LUXqu23, emergence trap (E3), 06.iv.1999, I. Schrankel.

Etymology

From Latin robustus (strong, robust); to be treated as an adjective, and referring to the strong anal point.

Diagnostic characters

Micropsectra robusta can be separated from other species in the atrofasciata group by the following combination of characters: Adult male with comparatively few microtrichia on wing surface; frontal tubercles small; antennal ratio c. 0.5; ultimate palpomere comparatively short (135 µm); pulvilli small, reaching base of claws; anal point strongly developed, robust, broad, apically blunt, knob between crests minute; superior volsella with few microtrichia on stem, setiger small, roundish, several long microtrichia in small field ventrally on setiger anterior to base of digitus, no apparent wrinkles ventroapically on setiger; digitus thin, slender, curved, apex pointed, reaching median margin of superior volsella; median volsella long and moderately thick, tip reaching well beyond posterior margin of superior volsella, with about 15 dorsomedially directed spoon-shaped lamellae on apex, setiform lamellae along whole length medially.

Description

Adult male. Measurements and ratios in Table 1.

Coloration: Body completely dark brown with even darker scutal stripes and eyes.

Head. Antenna with 13 flagellomeres. Frontal tubercles present, small (10 µm long); temporal setae in one row; palpomere three with 4 sensilla clavata in bundle.

Wing. Comparatively sparsely covered with macrotrichia in cells and on most veins, only about 25 macrotrichia in cell m 3+4, subcosta and media bare, brachiolum with 3 setae, squama bare.

Legs. Pulvilli small, reaching base of claws. Fore tibia with small scale, spur 20 µm long; middle and hind tibial combs 20 µm and 30 µm long, respectively; middle tarsomere Ta 1 with 2 sensilla chaetica.

Hypopygium ( Fig. 16A, B ). Anal tergite with tergite bands separate, posteriorly directed, almost reaching crests of anal point; 2 comparatively strong median tergite setae placed on low hump anterior to anal point base; 12 ventral apical setae. Anal point strong, robust, with comparatively short slightly curved anal crests, apex short, apically blunt; knob between crests present; comparatively small microtrichia free area around base. Setiger of superior volsella small, roundish with 8 dorsal and 2 median setae on setiger, 1 strong seta on stem; few dorsal microtrichia on stem and several long microtrichia ventrally on setiger, anterior to base of digitus; ventroapically wrinkles absent from setiger. Digitus, long, thin, slightly curved, reaching median margin of superior volsella. Median volsella long, moderately thick, apically pointed, with caudally and medially directed setiform and spoon-shaped lamellae, c. 15 spoon-shaped lamellae on apex; stem reaching well beyond superior volsella. Inferior volsella slightly club-shaped with moderately developed median and dorsoapical swelling, bearing numerous distal setae. Inner margin of gonocoxite with 3–4 strong setae.

Pupa and larva unknown.

Remarks

Unfortunately, only one male specimen of M. robusta has been available for examination. The species is nevertheless described as new to science since it shows a unique combination of characters (low AR, strong anal point, spoon-shaped lamellae limited to apex of median volsella).

Micropsectra robusta is known from the type locality only, a swampy area near a rheohelocrene spring. The once surrounding forest has been cleared, and vegetation near the spring now consists mainly of birch, broom, blackberries, raspberries, etc. ( Gerecke et al., 2005). The spring itself is relatively cold (7.4 °C in April 1999) and evenly flowing, and has moderate conductivity (207 µS/cm) ( Gerecke et al., 2005).

Figures

Figure 16. Micropsectra robusta sp. nov. A, hypopygium. B, superior, median and inferior volsellae.