Limnophyes minimus

Author: (Meigen, 1818)

Diagnosis (in part after Saether, 1990a - in italics)
Exuviae 1.7-3.0mm long (m=2.4mm, n=16).
Cephalothorax: Frontal setae on frontal apotome. Ocular field with 1 vertical and 1-2 postorbitals. Thoracic horn reduced to a small tubercle. Precorneal setae small. 2 Median and 1 lateral, fine antepronotals. Precorneal tubercle present, 3 fine and short precorneals. 4 Dorsocentrals; setal marks of setae 2 and 3 in contact. Thorax and wing sheaths smooth.
Abdomen: Tergite I without shagreen; II-VII with coarse and extensive shagreen; II-VIII with posterior transverse rows of translucent or slightly darkened elongate spines. Anterior points of tergite VII arranged in short transverse rows which form broken lines across the tergite. Tergites I(II)-VIII with at least the posterior margin armed with long narrow spines. Posterior long spines IV 40-67 (m=54, n=16), VI 26-52 (m=39, n=16). Longest spine IV 37-55µm long (m=45µm, n=18), VI 37-55µm long (m=47µm, n=17). Paratergite IV armed with small points. Pedes spurii Aand B absent. Sternite I without shagreen; II-VIII with medial shagreen; II-IV with very weak to well developed antero-median patches of 3-20 stronger points. Lateral setae of segment IV 75-110µm long (m=98µm, n=17). Segment VIII with 5 long lateral setae, fourth seta reduced, 0-45µm long.
Anal segment: Points on tergite IX robust, as strong as those on VIII, but much neater in appearance, the mid points of the central patch and lateral bands single and more or less equally distributed. Anal lobes smooth, somewhat rectangular, without fringe. Anal macrosetae of anal lobes long, 0.56-0.96x length of the anal lobe (m=0.70, n=17); setae thin and usually curved.
(Linked adult male: Langton and Pinder, 2003a)

Note: Very similar to the pupa of Limnophyes natalensis; both species may have 5 or 4 lateral setae on segment VIII and both have the sternites variably armed. A possible distinction upheld by the specimens to hand: in minimus the posterior points of tergite VIII are shorter than those on VII, whereas in natalensis they are longer.

This is a very variable form (as observed by Saether, 1990a) and although more than one species could be represented a handful of moss can produce specimens reflecting the whole range of variation known. Amongst the species for which pupae are known the general reduction in size of the lateral setae is indicative. Variation occurs in the position of dorsocentral setae 2 and 3 (which may be touching at their bases or separate), in the number of lateral setae on segment VIII and in the length of the apical setae of the anal lobes (which may be long and curved or short and nearly straight). Moreover, in some specimens the posterior segments may be nearly transparent.

Species keys out at Page 762: Orthocladiinae 174 Limnophyes of the Text Key.

Holarctic and Afrotropical (including Indian Ocean Islands); widespread in Europe.
(For more information see module IdentifyIt – file: Orthocladiinae).

Ecological notes
Seepages; damp rocks and soil: larvae in moss or wet dead leaves.
Damp soil but sometimes running water as on Gough Island. (Harrison, 2000a)