Key to the species of Lepidura

*The males of Lepidura callaina, L. improcera, L. mallecoensis, L. viridis, L. nigricephala sp. nov., L. patagonica sp. nov. and L. seminitida sp. nov. are unknown.

1 Propodeum with areola delimited by the median longitudinal, anterior transverse and posterior transverse carina (Fig. 3).... 2

- Propodeum without areola, even if with well delimited carina (Fig. 1), or with reduced carina, mostly smooth (Fig. 2)...... 3

2 Antenna with 43 flagellomeres; head green, except supra-antennal and ocellar areas, occiput and dorsal half of gena dark brown; propodeum dark brown, with areola centrally elongate........................ Lepidura improcera Dasch, 1974

- Antenna with 41 flagellomeres; head mostly black, with dark brown line between eye and gena; propodeum green, with small areola on anterior half............................................................... L. nigricephala sp. nov.

3 Propodeum smooth, with reduced carina (Fig. 2)............................................................. 4

- Propodeum with subpentagonal area delimited by complete lateral longitudinal and posterior transverse carina and incomplete anterior transverse and median longitudinal carina (Fig. 1)..................................................... 7

4 Antenna with 28–35 flagellomeres; T2 elongate,>2.55× as long as wide (dorsal view)............................... 5

- Antenna with 36–42 flagellomeres; T2 1.50–2.50× as long as wide (dorsal view)................................... 6

5 Hind femur very slender, 7.00× as long as wide; head green; mesosoma (except propodeum) yellowish brown, propodeum and metasoma mostly green................................................................ L. viridis Dash, 1974

- Hind femur stouter, up to ±6.50 × as long as wide; body mostly yellowish brown, dark brown in the following: supra-antennal area, area around ocelli, median and lateral stripes on anterior portion of mesoscutum, depression on pronotal lobe, proepisternum, dorsal portion of mesopleuron, mesosternum, metapleuron, propodeum, anterior margin of petiole and circular spots on anterior and posterior margins of T2–T3; metasoma olive green............................... L. tuberosa Dash, 1974

6 Length of T6–T9 (lateral view) greater than or equal to 1/3 of ovipositor sheath length; propodeum green; metasoma mostly green, T6–T9 mostly dark brown...................................................... L. collaris Townes, 1971

- Length of T6–T9 (lateral view): less than 1/3 of ovipositor sheath length; propodeum yellowish brown; metasoma mostly greenish brown, with petiole, T2 and anterior margin o T3 dark brown............................ L. olivacea Dash, 1974

7 Prothorax entirely black; subpentagonal area on propodeum only weakly delimited by longitudinal and transverse carina; median longitudinal carina weakly projecting towards central region of propodeum.............. L. tenebrosa Dash, 1974

- Prothorax almost entirely green (except pronotal lobe) or varying from light to dark brown, but never black; subpentagonal area on propodeum strongly delimited by longitudinal and transverse carina; median longitudinal carina never projected towards central region of propodeum...................................................................... 8

8 Metasoma elongated, T3–T6 longer than T1–T2............................................................. 9

- Metasoma stouter, T3–T5 shorter than T1–T2.............................................................. 11

9 Gena wide, about 1.00× as wide as eye in lateral view; head reddish brown, except antenna, supra-antennal area, area around ocelli and gena, dark brown; metasoma reddish brown, slightly darker on petiole and T2.......... L. variegata Dash, 1974

- Gena narrow, ±0.50× as wide as eye in lateral view; head and metasoma mostly green.............................. 10

10 T2 (dorsal view) 1.50–2.50× as long as its height; propodeum dark brown.................... L. mallecoensis Dash, 1974

- T2 (dorsal view)>4.80× as long as its height; propodeum green............................... L. patagonica sp. nov.

11 Propodeum yellowish brown......................................................... L. rubicunda Dash, 1974

- Propodeum green.................................................................................... 12

12 Areolet slightly petiolate; metasomal segments 6–9 dark brown................................ L. callaina Dash, 1974

- Areolet never petiolate; metasomal segments 6–9 mostly green................................................ 13

13 Gena wide,>0.75× as wide as eye in lateral view; mesosoma reddish brown, with darker spots on anterior region, especially on lateral lobes f mesoscutum, around tegula and anterior portion of mesopleuron; hind wing with two hamuli; anterior margin of T2 with dark brown spot............................................................. L. abbreviata Dash, 1974

- Gena narrow, ±0.70× as wide as eye in lateral view; pronotal lobe, mesoscutum and mesopleuron yellowish, without darker spots; hind wing with five hamuli; anterior margin of T2 and T3 with dark brown spots............. L. seminitida sp. nov.