Key to species of Limnophora Robineau-Desvoidy recorded from Macaronesia

Names in brackets refer to species recorded from the Canary Islands by mistake.

Males (sternite V large, emarginated at hind margin; abdomen obtuse)

1 Frons at narrowest point more than 0.25 times total head width................................................. 2

- Frons at narrowest point less than 0.25 times total head width.................................................. 7

2 One orbital seta....................................................................................... 3

- Two orbital setae..................................................................................... 4

3 Mesonotum matt brownish pruinose; in posterior view with paired, whitish grey dots in front of suture and in front of scutellum................................................................................ L. bipunctata (Stein)

- Mesonotum shiny black through sparse dark brown pruinosity; in posterior view only with a pair of silvery grey spots in front of scutellum........................................................................ L. nitidithorax (Stein)

4 Mid tibia with 2 pd setae inserted above and below the middle.................................................. 5

- Mid tibia with 1 pd seta inserted in the middle.............................................................. 6

5 Frons about one-third as wide as head. Dorsocentral setae 2 + 4. Fore leg simple. Sternite I bare.... L. exigua (Wiedemann)

- Frons about one-fourth as wide as head. Dorsocentral setae 2 + 3. Fore leg modified (Fig. 3B). Sternite I setulose.............................................................................................. L. flavitarsis Stein

6 Wing length <3.0mm. Frontal vitta velvety black; frontal triangle black, subshining. Presutural acrostichal field with setulae in three irregular rows...................................................................... L. beckeri (Stein)

- Wing length> 4.0mm. Frontal vitta velvety brown; large frontal triangle silvery grey pruinose. Presutural acrostichal field with setulae in two close-set rows.............................................................. L. riparia (Fallén)

7 Dorsocentral setae 2 + 4. Presutural acrostichal field with setulae in two or four rows, separated from dorsocentral rows by bare stripes.............................................................................................. 8

- Dorsocentral setae 2 + 3. Presutural acrostichal field with setulae in six rows leaving no bare stripes toward dorsocentral rows.................................................................................... L. quaterna (Loew)

8 Presutural acrostichal field with setulae in two rows......................................................... 9

- Presutural acrostichal field with setulae in four rows........................................................ 10

9 Calypteres dark brown infuscated, concolorous with wing base. Dorsal setulae on vein R 4+5 confined to radial node. Hind femur with pv setae confined to basal third.................................................... L. obscurisquama Stein

- Calypteres white, paler than wing base. Dorsal setulae on vein R 4+5 reaching from radial node and at least halfway to crossvein r‒m. Hind femur with a full length row of pv setae........................................... L. setinerva Schnabl

10 Frontal setae dorsally not quite reaching level of anterior ocellus, above them 1‒2 fine orbital setae. Sternite V without enlarged hind marginal setae.................................................................................. 11

‒ Frontal setae extended dorsally to level of anterior ocellus; orbital setae absent. Sternite V with a hind marginal row of enlarged setae (Fig. 11F)..................................................................... [L. tigrina (Am Stein)]

11 Frons at narrowest point less than 1.5 times as broad as ocellar tubercle (Fig. 6A). Upper part of fronto-orbital plate with 1(usually proclinate) orbital setula. Hind femur with 2(‒3) av setae................................................. 12

- Frons at narrowest point more than 2 times as broad as ocellar tubercle (Fig. 6D). Upper part of fronto-orbital plate with (1‒)2 reclinate orbital setae (stronger than uppermost frontal setae). Hind femur with 4‒6 av setae.......... L. paneliusi Emden

12 Calypteres brownish tinged toward margins, almost concolorous with wing base. Black scutal band broader, reaching behind insertions of third pair of postsutural dorsocentral setae. Surstyli broader (Figs 8E, F)............. L. obsignatula sp. nov.

- Calypteres whitish, much paler than wing base. Black scutal band narrower, its hind margin only reaching insertions of third pair of postsutural dorsocentral setae. Surstyli narrower (Figs 8B, C)......................... [L. obsignata (Rondani)]

Females (sternite V narrow; abdomen tapering)

1 One orbital seta....................................................................................... 2

- Two orbital setae..................................................................................... 3

2 Mesonotum matt brownish pruinose; in posterior view with paired, whitish grey dots in front of suture and in front of scutellum................................................................................ L. bipunctata (Stein)

- Mesonotum shiny black through sparse dark brown pruinosity; in posterior view only with a pair of silvery grey spots in front of scutellum........................................................................ L. nitidithorax (Stein)

3 Mid tibia with 1 pd seta inserted in the middle.............................................................. 4

- Mid tibia with 2(‒3) pd setae inserted above and below the middle.............................................. 5

4 Wing length <3.0mm. Frontal vitta velvety black; frontal triangle black, subshining. Presutural acrostichal field with setulae in three irregular rows...................................................................... L. beckeri (Stein)

- Wing length> 4.0mm. Frontal vitta velvety brown; large frontal triangle silvery grey pruinose. Presutural acrostichal field with setulae in two close-set rows.............................................................. L. riparia (Fallén)

5 Dorsocentral setae 2 + 3............................................................................... 6

- Dorsocentral setae 2 + 4............................................................................... 7

6 Mesonotum with a pair of small, oblong brown marks behind the suture. Sternite I bare............... L. quaterna (Loew)

- Mesonotum with a brownish black band immediately behind suture. Sternite I setulose................ L. flavitarsis Stein

7 Arista short-pubescent. Presutural acrostichal field with setulae in two close-set rows............................... 8

- Arista short-plumose. Presutural acrostichal field with setulae in four rows....................................... 9

8 Dorsum of thorax and abdomen intensely dark brown pruinose obscuring darker patterns on mesonotum and abdomen. Dorsal setulae on vein R 4+5 confined to radial node............................................... L. obscurisquama Stein

- Dorsum of thorax and abdomen greyish pruinose with distinct darker patterns on mesonotum and abdomen. Dorsal setulae on vein R 4+5 reaching from radial node and halfway to crossvein r‒m............................... L. setinerva Schnabl

9 Wing length> 3.5mm ................................................................................ 10

- Wing length <3.5mm ................................................................ L. exigua (Wiedemann)

10 Mesonotum with a broad, continuous black band behind the suture............................................ 11

- Mesonotum behind the suture with a pair of submedial black marks and a pair of smaller black marks laterally, above the wing bases............................................................................ [L. tigrina (Am Stein)]

11 Frons (Fig. 6C) with a broad band of dark brown pruinosity. Black scutal band almost straight at hind margin........... 12

- Frons (Fig. 6F) without a dark brown band. Black scutal band indented mesally and laterally at hind margin.................................................................................................. L. paneliusi Emden

12 Paired dark marks on tergite IV trapezoid, continuous with dark marks on preceding tergite......... L. obsignatula sp. nov.

- Paired dark marks on tergite IV subtriangular, widely separated from dark marks on preceding tergite................................................................................................... [L. obsignata (Rondani)]