Megaselia, Rondani, 1856

Disney, R. H. L. & Russell-Smith, A., 2014, Additions to the British list of Megaselia Rondani (Diptera: Phoridae), including two new species, from the crowns of ancient pollarded trees, Journal of Natural History 49 (25), pp. 1599-1626 : 1618-1624

Megaselia D&R-S sp. A

( Figures 23–24 )

This is probably a new species. However, the females of many species of Megaselia are unknown, are inadequately described or else have been incorrectly assigned to a species on the basis of co-occurrence at a locality on the same date.

The single specimen is a little damaged and with a quantity of debris adhering.

Female

Frons brown, clearly broader than long, with 40–44 hairs and dense but very fine microtrichia. SAs unequal, the lower pair at most two thirds as long as the upper pair. The antials about the same level on the frons as anterolaterals and upper SAs, and almost 3 times as far from upper SAs as from an anterolateral bristle. Pre-ocellars and mediolateral bristles almost equally spaced and at same level on frons. Cheek with three to five bristles and jowl with three that are longer. The subglobose postpedicels dusky yellow, without SPS vesicles. Palps whitish-grey, at most half as broad as postpedicel but about 1.8 times as long as breadth of latter, with five bristles and 10–13 hairs. Labrum pale yellow and about as wide as a postpedicel. Labella paler and their combined width about 1.7 times that of a postpedicel and with fewer than a dozen short spinules below each. Thorax mainly yellow above and brown on sides. Three notopleural bristles and no cleft in front of these. Mesopleuron bare. Scutellum with an anterior pair of hairs (about as large as those in middle of scutum) and a posterior pair of bristles. Abdominal tergites 1– 5 brown, T6 and T7 very faintly tinged brown and T8 devoid of pigment ( Figure 23 ). Venter light grey, and with hairs on segments 3–6. Sternite 7 represented by hairs only. Posterolateral lobes at rear of sternum 8 short. Cerci pale whitish-grey and about 2.7 times as long as broad. Furca brownish grey and as in Figure 24 . Dufour’ s crop mechanism not apparent. Legs yellow apart from brown patch on mid coxa and tip of hind femur. Fore tarsus with posterodorsal hair palisade on segments 1–4, and 5 a little shorter than 4. Dorsal hair palisade of mid tibia extends about 0.7 times its length. Hairs below basal half of hind femur longer than those of anteroventral row of outer half. Hind tibia with at least a dozen differentiated posterodorsal hairs, and spinules of apical combs simple. Wings 1.8–1.9 mm long. Costal index 0.49–0.50. Costal ratios 4.4:2.8:1. Costal cilia (of section 3) 0.09–0.10 mm long. Hair at base of vein 3 minute. With three axillary bristles, the outer being longer than costal cilia. Sc not reaching R1. Thick veins light brown, thin veins 4–6 a little darker and 7 pale. Membrane tinged grey (just evident to naked eye when viewed against a white background). Haltere knob pale dusky yellow.

Material

Vouche r female, Essex, Hatfield Forest (grid ref. TL5319 ), crown of ancient pollarded hornbeam ( Carpinus betulus ), 22.v–15.vi.2012 ( UCMZ, 20–179)

Revised couplets 79–81 of the keys to the males of the British species of Megaselia ( Disney 1989) .

The following three species recorded from mainland Europe are also included. M. pedatella (Schmitz) , whose recognition was clarified by Disney (2003), M. altezza Brenner (2006) and M. meridiana Brenner (2004) .

79 Haltere brown .................................................................................................. 82 – Knob of haltere yellow. (Hypopygium as in Figure 25 ) Body length less than 2 mm) ........................................................................................................ pedatella (Schmitz)

80 Anal tube clearly longer than midline length of dorsal face of epandrium ...... 81 – Anal tube subequal to or shorter than dorsal face of epandrium .................... 82

81 Hypopygium as in Figures 7A–B , each cercus having fewer than 10 hairs. The costal cilia (of section 3) less than 0.1 mm long. With only two bristles on axillary ridge ....................................................................................... russellsmithi Disney

– Hypopygium as in Figures 4A–B and 5B–C , each cercus having more than 10 hairs. The costal cilia more than 0.1 mm long. With three to four bristles on axillary ridge ......................................................................... henrydisneyi Durska

82 Left half of hypandrium lacks a lobe projecting rearwards ............................. 83 – Left lobe of hypandrium present ..................................................................... 84

83 Hypopygium as in fig. 314 (in Disney 1989), each cercus having more than 10 hairs. Mid and front tibiae yellowish ......................................... hortensis (Wood)

– Hypopygium as in fig. 316 (in Disney 1989), each cercus having less than 10 hairs. All femora dark brown ............................................................. alticolella (Wood)

84 Fifth segment of front tarsus clearly longer than fourth and all segments with a posterodorsal hair palisade (e.g. Figure 1A ) .................................................... 85

– Fifth segment of front tarsus about as long as fourth and lacking a posterodorsal hair palisade. (Hypopygium as in figs. 2–3 in Brenner 2006.) Wing length less than 1/ 5 mm. Costal cilia of section 3 less than 0.1 mm long. Hairs below basal half of hind femur shorter than those of anteroventral row of outer half) ...... meridiana Brenner

85 Palps yellow. Axillary ridge of wing with two to three bristles ....................... 86 – Palps brown. Axillary ridge of wing with four to five bristles. (Hypopygium as in fig. 1 in Brenner, 2004) ................................................................. altezza Brenner

86 Epandrium hairs about as robust as those at rear of abdominal tergite 6 ( Figure 2 ). Left lobe of hypandrium with microtrichia ( Figure 3 ) ................... ................................................................................................ crassipes (Wood)

– The hairs towards lower edges of epandrium thicker, bristle-like and clearly more robust than those at rear of T 6. Left lobe of hypandrium bare but with fine irregular fine fluting. ( Figure 6 ) ............................................ return to couplet 81

The precise numbers of each species trapped are not recorded, not least because there was a high frequency of teneral specimens which are frequently not readily identified

without the use of molecular barcodes. The numbers recorded below are for the minimum number of samples in which a species was obtained. The returns are for more than 30 traps. However, the catches were typically for several traps combined (ranging from 1 to 30 traps, but most frequently for five). In some cases, two or more samples were amalgamated. Furthermore, the duration for which a trap was set ranged from 24 to 63 days. These limitations preclude the use of statistical analysis, but the non-equivalent samples below do allow an indication of the relative abundances of the species.

The full list of Phoridae recorded from pitfall traps set in the crowns of ancient pollards in the South of England is as follows, with the localities abbreviated thus: BB = Burnham Beeches, Berks; BW = Bockhanger Wood, Merton Hatch, Kent; HF = Hainault Forest, Essex; HT = Hatfield Forest, Essex; WGP = Windsor Great Park, Berks; WW = Wytham Woods, Oxford; and the tree species thus: Cb = hornbeams ( Carpinus betulus ), Fs = beech ( Fagus sylvatica ), Q = oaks ( Quercus spp); samples from limes ( Tilia sp.) were mixed with those from beech, X = mixed samples from more one tree species. These codes are followed by the number of samples in each case.

The female attributed to Conicera tarsalis does not run to any of the species included in Buck’ s (2001a) incomplete key to the females of the European species of this genus.

The known larval habits are from the review in Disney (1994), except where indicated otherwise.

Anevrina thoracica (Meigen) Bb-X-2, HF-Cb-4, HT-Cb-1 = seven samples. Larvae reported from dead snails.

A. unispinosa (Zetterstedt) BB- X1, HT - Cb-1 = two samples. Larvae reported from invertebrate and vertebrate carrion.

Conicera floricola SchmitzBB-X2 = two samples.

C. tibialis SchmitzBW-Cb-1 = one sample. The larvae feed on vertebrate carrion (especially when buried in the soil).

Conicera sp. a female, possibly C. tarsalis Schmitz , whose female has not been adequately characterised BW-Cb-1 = one sample.

Diplonevra pilosella (Schmitz) BW-Cb-1 = one sample. It has been reared from a wounded earthworm ( Lumbricidae ).

Gymnophora quartomollis SchmitzWGP-Q1 = one sample.

Megaselia aculeata (Schmitz) BB-X1, HT-Cb2 = three samples.

M. altifrons (Wood) BB-X1, BW-Cb5, HF-Cb5, WGP-Q1, WW-Fs1 = 13 samples.

M. angusta (Wood) BW-Cb4, HF-Cb4, HT - Cb3 = 11 samples. It has been reared from invertebrate and vertebrate carrion, decaying fungi and plant material.

M. basispinata (Lundbeck) BB-X1, BW-Cb2, HF-Cb4, Ht-Cb1, WGP-Q2 = 10 samples.

M. breviterga (Lundbeck) BW - Cb1, HF-Cp1, WW-Q1 = three samples.

M. ciliata (Zetterstedt) HF -Cb - 2 = two samples. The larvae are predators of slug eggs ( Arion sp. and Deroceras sp.).

M. cinerea Schmitz BB-X-2, HT-Cb-1, WGP-Q-4 = seven samples.

M. diversa (Wood) BW-Cb4, HF-Cb2, HT - Cb - 1, WGP-Q - 1 = eight samples.

M. errata (Wood) BB-X - 3, WW-Fs1 = four samples. Buck (1997 b, 2001b) reported this species breeding in baits of dead snails.

M. funesta DisneyWGP-Q1 = one sample.

M. fungivora (Wood) BB-X1 = one sample.

M. giraudii (Egger) BB-X2, BW-Cb3, HF-Cb3, HT - Cb3, WGP-Q7 = 18 samples. SchmitzBB-X2, HT - Cb - 1, WGP-Q - 4 = seven samples. The larvae feed on a wide range of invertebrate and vertebrate carrion and other decaying matter.

M. henrydisneyi DurskaBB-X - 2, BW-Cb - 1, HT- Cb2, W-GPQ2 = seven samples.

M. hirtiventris (Wood) HT - Cb1 = one sample. The larvae develop in fungi. M. ignobilis (Schmitz) BW -Cb 1, HF -Cb 1, HT - Cb3 = five samples.

M. insons (Lundbeck) BB -X1, WGP - Q2 = three samples.

M. involuta (Wood) WGP-Q2 = two samples.

M. latipalpis (Schmitz) WGP-Fs1 = one sample.

M. longicostalis (Wood) BB-X - 1 BW- Cb- 3, HF-Cb4, WGP-Q1 = nine samples. The larvae feed on a wide range of invertebrate and vertebrate carrion and other decaying matter.

M. longifurca (Lundbeck) HF-Cb1 = one sample. The larvae prey on the eggs of spiders.

M. melanocephala (von Roser) BW-Cb1 = one sample. The larvae prey upon the eggs of the cave-dwelling spider. Meta menardi (Tetragnathidae) ,

M. nigriceps (Loew) BW- Cb4, HF-Cb3, HT-Cb1, WGP-Q1 = nine samples. It has been reared from a rotten willow log and dead insects.

M. pleuralis (Wood) BB-X2, BW-Cb 3, HF-Cb2, HT - Cb4 = 11 samples. It has been reared from bird and mammal dung and other decaying organic materials.

M. pseudogiraudii (Schmitz) BB-X1, BW-Cb6, HF-Cb7, HT-Cb3, WGP-Q3, WW- Fs2 = 22 samples.

M. pusilla (Meigen) HF-Cb1, HT-Cb1, WGP-Q - 1 = three samples.

M. pygmaea (Zetterstedt) WW- Fs1 = one sample.

M. rubescens (Wood) HT–Cb 2, WGP-Q 1 = three samples. It has been reared from a range of fungus sporophores.

M. ruficornis (Meigen) BW-Cb5, HF-Cb3, WGP-Q - 1 = nine samples. It has been reared from dung and vertebrate and invertebrate carrion.

M. rufipes (Meigen) BB-X4, BW-Cb6, HF-Cb - 6, HT-Cb- 4, WGP- Q 10 = 30 samples. The larvae exploit a wide range of decaying organic materials.

M. rupestris SchmitzHF- Cb 1 = one sample.

M. russellsmithi n. sp. WGP-Q2 = one sample.

M. serrata (Wood) WGP- Q2 = two samples.

M. shawi DisneyHF-Cb - 1 = one sample. It has been reared from the sporophore of a fungus ( Ševčík 2010).

M. speiseri SchmitzWGP -Q3 = three samples.

M. spinicincta (Wood) BB -X1 = one sample. It has been reared from fungus sporophores.

M. subcarpalis (Lundbeck) BW- Cb1, WGP- Q2 = three samples.

M. sylvatica (Wood) BB- X2 = two samples. It has been reared from the sporophores of fungi.

M. tenebricola SchmitzHT-Cb1 = one sample.

M. velutinicavus n. sp. HF-Cb1 = one sample.

M. sp. (female) D&R-S sp. AWW-Fs - 1 = one sample.

Figures

Figure 1. Megaselia crassipes male. (A) Posterior face of front tarsus; (B) left face of hypopytgium. Scale bar: 0.1 mm.

Figure 2. Megaselia crassipes male (synonym of M. basiturgida). (A) Left face of hypopygium; (B) posterior face of front tibia and basitarsus. Scale bar: 0.1 mm.

Figure 3. Megaselia crassipes male (synonym of M. gargarans), left face of anal tube.

Figure 4. Megaselia henrydisneyi male, hypopygium. (A) Left face; (B) right face. Scale bar: 0.1 mm.

Figure 5. Megaselia henrydisneyi male. (A) Frons (with bristles represented by their basal sockets only); (B) right face of hypopygium; (C) left face of hypopygium. Scale bars: 0.1 mm.

Figure 6. Megaselia henrydisneyi female, details of abdomen. (A) Left cercus; (B) lobes at rear of sternum 8; (C) tergites 5–7. Scale bars: 0.1 mm.

Figure 7. Megaselia russellsmithi male, hypopygium. (A) Left face; (B) right face (minus penis complex). Scale bar: 0.1 mm.

Figure 23. Megaselia D&R-S sp. A, female, dorsal face of abdomen.

Figure 24. Megaselia D&R-S sp. A, female, furca.

Figure 25. Megaselia pedatella male, left face of hypopygium. Scale bar: 0.1 mm.