Amathia brasiliensis Busk, 1886

Fehlauer-Ale, Karin H., Vieira, Leandro M. & Winston, Judith E., 2011, Molecular and morphological characterization of Amathia distans Busk and Amathia brasiliensis Busk (Bryozoa: Ctenostomata) from the tropical and subtropical Western Atlantic, Zootaxa 2962, pp. 49-62 : 52-56

Amathia brasiliensis Busk, 1886

( Figs 1, 2 , 5, 7, 9 ; Tables 1–2)

Amathia brasiliensis Busk, 1886: 34 , pl. 7, fig. 2; Osburn 1940: 339.

Amathia distans: Marcus 1937: 134 (part), pl. 27, fig. 72; 1955: 313 (part); Maturo 1957: 23, fig. 12; d’Hondt 1983: p. 65 (part). Non Busk 1886: 33.

Material examined. Lectotype (chosen here): NHMUK 1887.12.9.928 (slide mounted by A.B. Hastings using Borax-carmine Glycerine; Figures 1 and 2 ), Amathia brasiliensis (G. Busk det.), H.M.S. ‘ Challenger ’, Bahia ( Brazil), 10–20 fms (18.29–36.58 m). Paralectotypes: NHMUK 1887.12.9.927, Amathia brasiliensis (G. Busk det.), H.M.S. ‘ Challenger ’, Bahia ( Brazil), 10–20 fms (18.29–36.58 m); NHMUK 1890.4.14.5, Amathia brasiliensis , Bahia ( Brazil), G. Busk Supplementary Collection; NHMUK 1899.7.1.4520, Amathia brasiliensis , H.M.S. ‘ Challenger ’, Bahia ( Brazil), G. Busk Collection; NHMUK 1963.2.12.356, Amathia brasiliensis , H.M.S. ‘ Challenger ’, Bahia ( Brazil), Dundee Collection. Additional material ( Table 1): MZUSP 495, MZUSP 505 (donated to NHMUK), Maceió, Alagoas State, Brazil; MZUSP (492, 493), MZUSP (504, 506) (donated to NHMUK), São Sebastião, São Paulo State, Brazil; MZUSP 494, Ilhabela, São Paulo; MZUSP (496, 497), MZUSP 507 (donated to NHMUK), São Francisco do Sul, Santa Catarina State, Brazil.

Redescription. Colonies cuticularized, erect, densely branched, brownish. Frontal surface of stolons and zooids delicate, with inconspicuous whitish-pale pigment spots observed only in living colonies; colonies in alcohol whitish-brown in color. Autozooids in biserial clusters, 8 to 18 pairs in long complete clockwise or anticlockwise spirals along a wide stolon; the direction of spirals maintained from maternal to daughter stolons. Clumps occupying from half to three quarters of distal portion of stolon. Autozooids tubular, most of them almost completely unjoined, rarely joined at one third of their total length, not varying in size. Orifice terminal, approximately subquadrangular. Rhizoids sometimes present, arising in the proximal end of stolon. Polypides with 8 equal straight tentacles, measuring approximately 0.27 mm in length.

Remarks. Amathia brasiliensis was originally described from Bahia State, Brazil ( Busk 1886). This species is characterized by whitish-pale pigment spots in the frontal surface of stolons and zooids, and by a wide stolon (about 0.22 mm of diameter) with biserial zooid clusters growing in clockwise or anticlockwise spirals along it.

Busk (1886) noted a tendency of direction of spirals, characteristic of this species. Osburn (1940) disagreed with the synonymization of the name A. brasiliensis under A. distans adopted by Marcus (1937), and used the epithet brasiliensis for specimens with wider stolons (0.18–0.30 mm). The North Carolina specimens reported by Maturo (1957) under the name A. distans have a wider stolon than A. distans from Brazil (see Tables 2–3 for comparison), and hence probably belong to A. brasiliensis .

Specimens from the Suez Canal collected by Hastings (1927), registered as Amathia ? brasiliensis (NHMUK 1926.9.6.25), have stems with similar diameters (0.18–0.20 mm) to those of A. brasiliensis Busk , but have smaller and broader free ends of zooids than the ‘Challenger’ specimens of A. brasiliensis . D’Hondt (1983) redescribed the Suez Canal material as Amathia distans var. aegyptiana , which was later raised to specific rank as Amathia aegyptiana by Chimonides (1987). The rooting processes are present in both A. brasiliensis and A. aegyptiana and the long bare terminal ramification, rarely present in A. brasiliensis , was not described for A. aegyptiana .

Chimonides (1987), although noticing some similarities among Amathia pruvoti , A. distans , A. aegyptiana and A. brasiliensis , observed several morphological characteristics that support each one as a distinct entity. These include the spiraling pattern of autozooidal groups (close to 360° in the last three species), the production of rhizoids only by A. brasiliensis , and the autozooidal spirality direction between maternal and daughter stolons. According to Chimonides (1987), A. aegyptiana is the only one that produces autozooidal groups in which the direction of the spirality is maintained. Another distinctive character of A. aegyptiana is the absence of rhizoids [according to Chimonides (1987) and Souto et al. (2010)], but this structure is inconstant among the different specimens of A. brasiliensis studied in the Western Atlantic and could represent ecophenotypical variation.

Autozooid length

Min-Max - 0.320–0.580 0.300–0.680 0.340–0.540 0.390–0.520 0.410–0.570

Mean (SD) - 0.422 (0.068) 0.300 (0.124) 0.450 (0.058) 0.440 (0.046) 0.454 (0.050)

Autozooid width

Souto et al. (2010) described Amathia minoricensis from Balearic waters (Iberian Peninsula), in which the direction of twisting remains the same as that of the maternal stolons. Although A. brasiliensis and A. minoricensis present overlapping measurements for autozooids and stolon width [page 189 of Souto et al. (2010); Table 2 of this study], the latter species is readily distinguished by the helix of autozooids describing about 180–250°, the autozooids being joined for almost their total length, and the length of the stolon and zooid cluster being shorter in A. brasiliensis than in A. minoricensis . Souto et al. (2010) also noted differences between the spiraling direction of A. aegyptiana and A. brasiliensis , which according to them is not conserved along the colony of the latter species. However, in all specimens of A. brasiliensis here analyzed, including the type specimens, the direction of twisting is conserved along the colony. Busk (1886: p. 34) also noted for A. brasiliensis that the “comparative distinctness of the zooecia in the spiral series shows a tendency in the same direction”.

Biological notes. In Brazil, A. brasiliensis is common on various substrata, including algae, bryozoans and anthropogenic surfaces, and was observed also on or with other vesiculariids, such as A. distans , Amathia cf. vidovici , Amathia cf. crispa and Z. verticillatum .

Distribution. Western Atlantic: North Carolina ( Maturo 1957), Bermuda, Porto Rico ( Osburn 1940), and Brazil ( Vieira et al. 2008). Brazil: Fernando de Noronha Island, and states of Alagoas, Bahia, São Paulo and Santa Catarina.

Figures

FIGURES 1 – 4. 1 – 2, Amathia brasiliensis, NHMUK 1887.12. 9.928 (lectotype specimen, chosen here), off Bahia, Brazil; 3 – 4, Amathia distans, NHMUK 1887.12. 9.925 (lectotype specimen, chosen here), off Bahia, Brazil.

FIGURES 5 – 10. 5, Amathia brasiliensis, general view of the whitish-pale living colony; 6, Amathia distans, general view of the bright yellow living colony; 7, A. brasiliensis, close-up of the biserial autozooidal clusters around the wide stolon; 8, A. distans, close-up of autozooidal clusters around the slender stolon; 9, A. brasiliensis, close-up of whitish-pale pigment spots in the frontal surface of stolon and zooids; 10, A. distans, close-up of bright yellow pigment spots in stolon and zooidal surfaces, including lophophores.

Tables

TABLE 2. Measurements (n = 10) and selected characters of Amathia brasiliensis Busk, 1886 from the Brazilian coast. NHMUK MZUSP MZUSP MZUSP MZUSP MZUSP 1887.12. 9.928 505 495 493 496 504

Min-Max	-	0.080–0.160	0.080–0.130	0.090–0.140	0.090–0.160	0.100–0.130
Mean (SD)	-	0.118 (0.024)	0.106 (0.16)	0.107 (0.020)	0.121 (0.019)	0.116 (0.008)
Stolon length
Min-Max	-	1.131–1.755	1.404–2.145	1.365–2.028	1.482–2.145	1.872–2.340
Mean (SD)	-	1.446 (0.182)	1.720 (0.199)	1.692 (0.205)	1.841 (0.199)	2.086 (0.145)
Stolon width
Min-Max	-	0.150–0.210	0.150–0.260	0.150–0.210	0.170–0.260	0.170–0.240
Mean (SD)	~ 0.22	0.179 (0.018)	0.199 (0.031)	0.177 (0.020)	0.216 (0.029)	0.196 (0.026)