Tethylembos Myers, 1988

Ariyama, Hiroyuki & Kodama, Masafumi, 2024, Three species of the family Aoridae Stebbing, 1899 (Crustacea: Amphipoda) collected from remote islands in southern Japan, with a key to all Japanese species of the family, Zootaxa 5433 (4), pp. 500-528 : 510-512

Tethylembos Myers, 1988

[Japanese name: Maeashi-yokokoebi-zoku]

Tethylembos Myers, 1988a: 191 .—J.L. Barnard & Karaman, 1991: 236.— Myers & Lowry, 2003: 465.

Type species. Lembos viguieri Chevreux, 1911 , monotypy.

Diagnosis [after Myers (1988a)]. Mandibular palp article 3 longer than article 2, ventral margin straight, marginal setae of two distinct lengths, but terminal setae longer; left mandibular molar with oblique lamellae extending across half width of molar surface from marginal lappets; male gnathopod 1 with propodus enlarged, a little longer than carpus; female gnathopod 1 not like that of male; uropod 3 peduncle short, expanded, outer ramus with long marginal setae, extremely long distal setae and a small second article.

Included species (3). Tethylembos cavatus sp. nov.; T. japonicus Ariyama, 2004 ; and T. viguieri ( Chevreux, 1911) .

Remarks. Only Tethylembos and Archaeobemlos have the left mandibular molar with oblique lamellae ( Table 1 ); however, the mandibular palp article 3 is straight and longer than article 2 in Tethylembos (vs. falcate and shorter than article 2 in Archaeobemlos ). Tethylembos closely resembles Bemlos in all features except for the left mandibular molar. The known Bemlos species possibly include some Tethylembos species, because structure of the mandibular molar has not been observed sufficiently in many species. In fact, Bemlos pualani (J.L. Barnard, 1970) is very similar to the Tethylembos species ( Ariyama 2004a).

Key to species of the genus Tethylembos in the world (adult males)

1. Pereopod 5, posterodistal part of basis excavated.............................................. T. cavatus sp. nov.

- Pereopod 5, posterior margin of basis smooth............................................................... 2

2. Coxa 1 anteroventral corner weakly projected, gnathopod 1 propodus ca. 1.5–1.8 times length of carpus............................................................................................... T. japonicus Ariyama, 2004

- Coxa 1 anteroventral corner acutely projected, gnathopod 1 propodus ca. 1.2–1.5 times length of carpus.............................................................................................. T. viguieri ( Chevreux, 1911)