Mexichromis, Bertsch, 1977

Tibiriçá, Yara, Pola, Marta & Cervera, Juan Lucas, 2017, Astonishing diversity revealed: an annotated and illustrated inventory of Nudipleura (Gastropoda: Heterobranchia) from Mozambique, Zootaxa 4359 (1), pp. 1-133 : 39

Mexichromis sp.

( Figure 11 E–F , 12 A–D )

Material examined. Seven specimens. MB28-004587, ZDRS, 21 Jun. 2012, 30m, 18mm; MHN-YT1223 3spcs., POD, 11 May 2014, 15m, 11–14mm; MB28-004850, 3 spcs., POD, 11 May 2914, 15m, 11–22mm.

Habitats. Subtropical rocky reefs.

Occurrences. Ponta do Ouro and Zavora.

Geographic distribution. Western Indian Ocean. South Africa ( Rudman 1999a) and Mozambique.

Remarks. Mexichromis sp. is externally similar to M. mariei ( Crosse, 1872) . Based on external morphology, Rudman (1999a) was unsure if this species was M. mariei or a different species because of inconsistencies in colour pattern between M. mariei from the Pacific and M. cf. mariei from the western Indian Ocean. Therefore, we examined the radula of one specimen and confirmed Rudman’s (1999a) belief that this species is different from M. mariei . While the radula formula for M. mariei is 55x 27.0.27 (+3) ( Rudman 1983), in the specimen examined it is 22x 15.0.15 (+3) ( Fig. 12 A ). Moreover, the very long lateral teeth clearly distinguish these species. The cusp of the lateral tooth is round and the number of denticles varies from two to four ( Fig. 12 B ). The innermost tooth has a wider base and four denticles on the outer side; these denticles gradually reduce in size from the cusp to the base ( Fig. 12 C–D ). In the inner side of the innermost teeth there are one or two denticles ( Fig. 12 C ).

Figures

FIGURE 11. A, Hypselodoris pulchella (MB28-004553). B, Hypselodoris regina (ZMBN117025). C, Hypselodoris rudmani (MB28-004471). D, Mexichromis cf. katalexis (MHN-YT672). E–F, Mexichromis sp. (MB28-004587 and MB28-004850, respectively). G–H. Miamira magnifica (MB28-004948 and MB28-004986, respectively). I, Miamira miamirana (MB28- 004907).J, Miamira moloch (MB28-004921). K, Miamira sinuata (MB28-005102). L, Thorunna africana (MB28-004889).

FIGURE12. RadulaMexichromis sp.(MB28-004850), SEMs of radula.A, General view of the radula.B, Left outermost teeth from the anterior part.C, Innermost teeth.D, Central right lateral and outermost teeth.