Megaselia horrenticauda, DISNEY & WINQVIST, 2018

DISNEY, R. Henry L. & WINQVIST, Kaj, 2018, New records including new species of Megaselia Rondani and Triphleba Rondani (Diptera: Phoridae) from Finland, Fragmenta Faunistica 61 (1), pp. 11-33 : 16-17

Megaselia horrenticauda n. sp.

( Figs 18–27 )

Dia gno sis (male). In the key to the males of the British species ( Disney 1989) it runs to couplet 161, but as the epandrial hairs are somewhat robust along the lower margins one could take either option. At couplet 162 lead 1 is for M. spinicincta (Wood) , whose hypopygium resembles the new species but with a shorter dorsal face to the epandrium ( Figs 28–30 ). In addition it has only two bristles on the notopleuron, a costal index less than 0.5 ( Fig. 32 ) and a posterodorsal hair palisade on segment 1–4 of the front tarsus ( Fig. 31 ). Taking lead 2 at couplet 162 one proceeds to couplet 187, where the choice is between the vein Sc running to vein 1 or falling just short of it. As the Sc is only just short of vein 1 ( Fig. 27 ), at low magnifications it may appear to join vein 1. Taking the first option one proceeds to couplet 194, to M. rubella (Schmitz) , whose epandrium has fewer and much finer hairs; as does the subsequently described M. kanoi Disney that runs to the same point. Taking the second option at couplet 187 one proceeds to couplet 204, where the separation is between a yellow haltere knob or one that is variably darker. The first option leads to couplet 232, lead 2, where one is returned to a complex that all have fewer and weaker epandrial hairs. Taking the second option from couplet 204 one arrives at couplet 388 and M. invernessae Disney , whose epandrial hairs are likewise weaker and fewer. Indeed the hypopygium of the new species is closer to M. spinicincta than to any other subsequently described species running to any of the above couplets.

Male. Frons as Fig. 18 and with dense but very fine microtrichia. Cheek with 5–7 fine bristles and jowl with a single very long bristle. Postpedicels as Fig. 19 and without SPS vesicles. Palps yellow, about a third as broad as postpedicel, with 4 bristles and as many hairs. Labrum pale. Labella as Fig. 20 . Thorax brown. Three notopleural bristles, but the middle one is the smallest ( Fig. 21 ) and no cleft in front of these. Mesopleuron bare. Scutellum with an anterior pair of small hairs and a posterior pair of bristles. Abdominal tergites brown with numerous hairs that are longest posterolaterally on T6. Venter brown, and with hairs on segments 3–6. Hypopygium as Figs 22–23 . Legs yellow apart from brown tip to hind femur.

Fore tarsus with posterodorsal hair palisade on segments 1–3 only ( Fig. 24 ). Dorsal hair palisade of mid tibia extends about 0.6 times its length. Hind femur and tibia as Fig. 25 . Hind tibia with up to 24 only moderately differentiated posterodorsal hairs, without anterodorsals, and spinules of apical combs simple. Wings ( Figs 26 & 27 ) 2.0– 2.2 mm long. Costal index 0.52. Costal ratios 2.0: 0.9: 1. Costal cilia (of section 3) 0.07 mm long. No hair at base of vein 3. With 2 unequal axillary bristles, the outer be 0.13 mm long. Haltere knob pale gray.

Material exa mined. Holotype male, Finland, Lkor : Savukoski, Ainijärvi 7522293:3603111, 31 Jul–28 Sep 2015, J. Salmela leg. (Malaise trap) ( UCMZ, 34-190 ). Paratype male as holotype .

Et y mo lo g y. From horrentis (bristly) and cauda (tail) referring to epandrium.

Figures

Figs 18–23. Megaselia horrenticauda n. sp. male: 18 – frons; 19 – postpedicels; 20 – labella and palps; 21 – notopleuron; 22–23 – hypopygium.

Figs 24–27. Megaselia horrenticauda n. sp. male: 24 – front tarsus; 25 – hind femur and tibia; 26 – wing; 27 – subcosta.

Figs 28–30. Megaselia spinicincta (Wood) male: 28–30 – hypopygium.

Figs 31–32. Megaselia spinicincta (Wood) male: 31 – front tarsus; 32 – wing.