Microcassiope minor

Microcassiope minor (Dana, 1852)

(Figs. 37A–F, 38A–E, 39A–C)

Xantho minor Dana, 1852a: 169 [Type locality: “ Probably Madeira ”; possibly the Cape Verdes, v. original description].

Trindade specimens. 1 female (MZUSP 41070), Brazil, off Espírito Santo, Trindade Island, Ponta da Calheta, 20º30’18.72”S, 29º18’31.6”W, J.B. Mendonça coll., 25.vii.2018, 15.6 m. 1 male (MZUSP 40847), 1 female (MZUSP 41292), ibidem, Praia do Noroeste, 20º29’46.4”S, 29º20’35.4”W, J.B. Mendonça coll. 30.vii.2018, 9 m. 1 female (MZUSP 40845), ibidem, 28.xi.2017, 9.4 m. 2 males, 4 females (2 juveniles) (MZUSP 40323), ibidem, 20º29’48.14”S, 29º20’35.21”W, J.B. Mendonça coll., 13.ii.2019, 4 m. 1 male, 2 females (MZUSP 41294), ibidem, Enseada da Cachoeira, Farrilhões, 20º31’22.4”S, 29º19’52.0”W, J. M. Mendonça coll., 9.vii.2013, 10.4 m. 1 male (MZUSP 41295), ibidem, 4.iv.2014, 12.2 m. 1 male (MZUSP 41296), ibidem, 20º29’52.3”S, 29º19’15.6”W, J. M. Mendonça coll., 17.iv.2014, 13.3 m. 1 ovigerous female (MZUSP 40935), ibidem, 20º31’29.8”S, 29º19’52.0”W, J. M. Mendonça coll., 21.xi.2017, 11.3 m. 1 male, 1 female (MZUSP 41297), 1 female (MZUSP 41300), ibidem, Praia da Calheta, 20º30’29.5”S, 29º18’37.0”W, J.B. Mendonça coll., 20.vi.2016, 8.2 m. 4 males, 4 females (MZUSP 41092), ibidem, 20º30’18.72”S, 29º18’31.67”W, J.B. Mendonça coll., 26.x.2014, 9.9 m. 1 male (MZUSP 41081), ibidem, Enseada Praia do Príncipe, Ilha Sul, 20º31’34.32”S, 29º19’27.98”W, J.B. Mendonça coll., 6.xi. 2014, 17.6 m. 1 male (MZUSP 33734), ibidem, Enseada das Orelhas, 20º29’40.2”S, 29º20’32.9”W, J.B. Mendonça coll., 18.iv.2014, 12.1 m. 1 female (MZUSP 33829), ibidem, 1.xi.2014, 12 m. 1 ovigerous female (MZUSP 33820), ibidem, 21.vii.2015, 15 m. 1 male (MZUSP 40842), ibidem, 6.xii.2017, 8.4 m. 1 female (MZUSP 33728), ibidem, Enseada dos Portugueses, Farol, 20º29’52.3”S, 29º19’15.6”W, J.B. Mendonça coll., 20.v.2014, 13.1 m. 1 male (MZUSP 33819), ibidem, 4.viii.2015, 10 m. 1 female (MZUSP 40937), ibidem, 4.xii.2017, 12.7 m. 2 males (MZUSP 41032), ibidem, Ponta do Monumento, 20º30’10.3”S, 29º20’36.1”W, J.B. Mendonça coll., 30.vi.2013, 19.5 m.

Size of largest male: cl 6 mm, cw 8.9 mm; largest female: cl 8.1 mm, cw 11.1 mm.

Comparative material examined. Microcassiope minor: East Atlantic: Gulf of Guinea, 4 males, 2 females (USNM 170123), southwest of Annobon, 01º28’S, 05º36’E, R/V “Pittsbury”, stn 282, 21.v.1965, 23 m. Central Atlantic: 1 male (USNM 256635), Ascension Island, English Bay, Rocky Spit, R.B. Manning coll., 22.v.1971, intertidal pool and rocky shore, some coarse sand bottom [R. B. Manning det.]. 1 male (USNM 112506), St. Helena Island, Ruperts Bay, 15º55’S, 05º43’W, A. Loveridge coll., 18.iii.1960 [R. B. Manning det.].

Distribution. Amphi-Atlantic. Western Atlantic: Bahamas, Gulf of Mexico, Cuba, Curaçao, and Venezuela (Felder et al. 2009). This is the first record of M. minor from Brazil (Trindade Island). Central Atlantic: Ascension (Manning & Chace 1990) and Saint Helena (Chace 1966). Eastern Atlantic: from the eastern Mediterranean, Azores, Canary Islands, Madeira, Cape Verde, and Gulf of Guinea (Manning & Holthuis 1981, and references therein).

Ecological notes. Shallow waters, usually from shore under stones to depths of 45 m (Manning & Holthuis 1981), occasionally 220 m (Türkay1976). Ovigerous females were recorded from Saint Helena in January and April

(Chace 1966). Microcassiope minor is very common in Trindade where it was commonly associated with calcareous algae, between 4 and 19.5 m. Its first zoeae stage was decribed by Clark et al. (2004). The variable color pattern is illustrated in Fig. 37A–E.

Remarks. The taxonomy of Xantho minor Dana, 1852 was stabilized by Monod (1956), who clarified that X. minor (currently Microcassiope minor) is conspecific with Xanthodes rufopunctatus A. Milne-Edwards, 1869 (type species of Microcassiope Guinot, 1967), and also by Chace (1966) who showed that the western Atlantic Pilumnus granulimanus Stimpson, 1871a, is a more recent synonym of M. minor.

Guinot (1971: 1076) removed M. granulimana (Stimpson) from the synonym of M. minor (Dana) while providing no reasons to support her judgement. Manning & Holthuis (1981) reduced again M. granulimana into a junior synonymy of M. minor.