Maera Leach 1814
Creators: name: Ariyama, Hiroyuki
name: Kodama, Masafumi
name: Tomikawa, Ko
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Melitidae
Maera

description: Key to adult males of Japanese species of the Maera -clade (revised).
Quadrimaera angulata sp. nov. is not included because the male is unknown.
1. Gnathopod 2, anterior margin of dactylus bearing many setae.................................................. 2
- Gnathopod 2, anterior margin of dactylus with single seta..................................................... 4
2. Body very large (maximum BL:> 50 mm), gnathopod 2 palm defined by tooth bearing strong robust seta............................................................................................ Maera loveni (Bruzelius, 1859)
- Body small (maximum BL: about 10–16mm), gnathopod 2 palm defined by tooth bearing small robust seta.............. 3
3. Small notches present on coxae 1–6.................................................... Maera denticoxa sp. nov.
- Small notches present on coxae 1–3............................................ Maera sagamiensis Ariyama, 2020
4. Pereopods 3–7 dactyli bifid............................................................................. 5
- Pereopods 3–7 dactyli simple............................................................................ 8
5. Gnathopod 2 palm with 2 excavations in middle.............................. Quadrimaera quqdrimana (Dana, 1853)
- Gnathopod 2 palm with single excavation in middle.......................................................... 6
6. Excavation on gnathopod 2 palm quadrate................................... Quadrimaera gotoensis Ariyama, 2019
- Excavation on gnathopod 2 palm rounded.................................................................. 7
7. Pereopod 6, posterior margin of basis heavily setose............................ Quadrimaera setibasis Ariyama, 2019
- Pereopod 6, posterior margin of basis not setose........................... Quadrimaera pacifica (Schellenberg, 1938)
8. Uropod 3, tips of both rami pointed......................................... Austromaera ariakensis Ariyama, 2019
- Uropod 3, tips of both rami truncate...................................................................... 9
9. Gnathopod 2 basis wide; uropod 3 rami long, about 3 times length of peduncle........ Meximaera mooreana (Myers, 1989)
- Gnathopod 2 basis ordinary; uropod 3 rami relatively short, 1 – 2 times length of peduncle........................... 10
10. Gnathopod 2 palm transverse, without robust setae; mandibular palp article 1 with distal tooth....................... 11
- Gnathopod 2 palm slightly or moderately oblique, with many robust setae; mandibular palp article 1 lacking distal tooth.. 12
11. Uropod 3 longer than uropod 2, basis of pereopod 5 subovate.................... Maeropsis okinawensis Ariyama, 2018
- Uropod 3 shorter than uropod 2, basis of pereopod 5 subrectangular.............. Maeropsis serratipalma (Nagata, 1965)
12. Palm of gnathopod 2 moderately oblique (angle of palmar corner: 115–130°)..................................... 13
- Palm of gnathopod 2 slightly oblique (angle of palmar corner: 90–105°)......................................... 14
13. Coxa 1 anteroventral corner produced acutely, distal robust setae of telson short (ca. 20% of telson length).................................................................................... Orientomaera obliquua Ariyama, 2018
- Coxa 1 anteroventral corner rounded, distal robust setae of telson long (ca. 45% of telson length)......................................................................................... Orientomaera rotundicoxa Ariyama, 2018
14. Palm of gnathopod 2 with two distinct teeth.................................... Orientomaera incisa Ariyama, 2020
- Palm of gnathopod 2 with several blunt teeth.............................................................. 15
15. Posterior margin of pereopod 6 basis almost straight, body color bluish pale pink................................................................................................... Orientomaera brevispina (Kim & Kim, 1991)
- Posterior margin of pereopod 6 basis convex, body color light crimson............ Orientomaera decipiens Ariyama, 2018
description: Published as part of Ariyama, Hiroyuki, Kodama, Masafumi & Tomikawa, Ko, 2020, Species of the Maera-clade collected from Japan. Part 4: addenda to genera Maera Leach, 1814 and Quadrimaera Krapp-Schickel & Ruffo, 2000, with revised keys to Japanese species of the clade (Crustacea: Amphipoda: Maeridae), pp. 336-352 in Zootaxa 4885 (3) on page 350, DOI: 10.11646/zootaxa.4885.3.2, http://zenodo.org/record/4296670