Alexandrella Chevreux, 1911 1911
Creators: name: Souza-Filho, Jesser F.
name: Guedes-Silva, Elkênita
name: Andrade, Luiz F.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Stilipedidae
Alexandrella

description: Key to world species of Alexandrella (adapted from d’Udekem d’Acoz and Verheye 2017)
1a. Pereonite 7 with a strong dorsal pointed carina.................................................................. 2
1b. Pereonite 7 dorsally smooth ....................................................................................................... 7
2a. Article 1 of peduncle of antenna 1 with short dorsomedial tooth; dactylus of pereopods 3–4 long; posteroventral border of coxa 4 straight or nearly so .......... 3
2b. Article 1 of peduncle of antenna 1 with long dorsomedial tooth; dactylus of pereopods 3–4 short; posteroventral border of coxa 4 strongly concave .............. 5
3a. First posterodorsal carina on pereonite 7 .............................................................................. 4 3b. First posterodorsal carina on pereonite 6 ..................... ..................... Alexandrella sp. 1 * 3c. First posterodorsal carina on pereonite 5 or more anterior pereonite(s) ........................ ................................................................................................................................ Alexandrella sp. 2 *
4a. Telson 0.37 cleft ........................................ Al. schellenbergi (Holman and Watling, 1983) 4b. Telson 0.2 cleft or less ...................................... Al. pulchra Ren in Ren and Huang, 1991
5a. Anteroventral lobe of head moderately developed, triangular or bluntly triangular; dorsal carina of pleonite 3 with straight profile; posterodistal corner of basis of pereopod 6 broadly rounded ....................................................................................................... 6
5b. Anteroventral lobe of head very strong, hemi-elliptic; dorsal carina of pleonite 3 with distinctly sigmoid profile; posterodistal corner of basis of pereopod 6 forming a blunt squared angle ........... ........... Al. chione d’Udekem d’Acoz and Verheye, 2017
6a. Pereonite 6 with small posterodorsal carina; crest of urosomite 1 with long posterior tooth and deep posterior notch .............................................. Al. australis (Chilton, 1912) 6b. Pereonite 6 without posterodorsal carina; crest of urosomite 1 with small posterior carina and no posterior notch .................................................................. Alexandrella sp. 3 *
7a. Telson truncate, notched or cleft but not convex .............................................................. 8 7b. Telson convex and entire (carina of urosomite 1 compact, not elongate) .................... ....................................................................................... Al. polarsterni (Berge and Vader, 2005)
8a. Gnathopods 1–2 subchelate ......................................................................................................... 9 8b. Gnathopods 1–2 simple .............................................................................................................. 10
9a. Gnathopods 1–2 lacking facial setae; pleonites 1–2 with a weak dorsal ridge; pleonite 3 with a low rounded carina .... Al. subchelata Holman and Watling, 1983 9b. Gnathopods 1–2 densely setose; pleonites 1–3 with a dorsal well-developed pointed carina ........................................................................................ Al. setosa Serejo, 2014
10a. Pleonites 1–3 strongly toothed; female pereopod 1 with oostegite ....................... 11 10b. Pleonites 1–3 weakly toothed or absent; female pereopod 1 without oostegite 12
11a. Right mandible with lacinia mobilis reduced to a simple tooth ......................................... ...................................................................................... Al. mandibulata Berge and Vader, 2005 11b. Right mandible with lacinia mobilis broad and toothed, but smaller than left one .. ................................................................................................. Al. martae Berge and Vader, 2005
12a. Mandibular incisors not toothed along the entire margin; antennae 1–2 subequal in length .................................................................................................................................................. 13 12b. Mandibular incisors toothed along the entire margin; antenna 1 shorter than antenna 2 ........................................................................................................................................ 14
13a. Pereonites 1–7 with a pair of lateral triangular teeth.. .. Al. dentata Chevreux, 1912 13b. Pereonites 1–7 smooth ................................................................ Al. mixta Nichols, 1938 s. l.
14a. Mandible right lacinia mobilis absent; epimeron 3 posteroventral corner rounded; telson entire......................... ......................... Al. inermis Bellan-Santini and Ledoyer, 1987 14b. Mandible right lacinia mobilis present and well developed; epimeron 3 posteroventral corner pointed; telson cleft .......................................................... Al. cedrici sp. n. (*) in d’Udekem d’Acoz and Verheye (2017).
description: Published as part of Souza-Filho, Jesser F., Guedes-Silva, Elkênita & Andrade, Luiz F., 2024, Four new species and two new records of deep-sea Amphipoda (Crustacea: Peracarida) from Potiguar Basin, north-eastern Brazil, pp. 1615-1655 in Journal of Natural History 58 (41 - 44) on pages 1649-1650, DOI: 10.1080/00222933.2024.2374404, http://zenodo.org/record/13758699