Adeonella haywardii, Amui, 2005

Amui, Ann-Margret, 2005, Adeonellas from the Gulf of Aden including one new species, Zootaxa 1012 (1), pp. 45-52 : 48-50

Adeonella haywardii n. sp.

Figure 2, 3–8

Type Material examined: Holotype. Inner Gulf of Aden ; 12° 30.9N, 44° 47.7E; 76m, 06.03.1987, Meteor Station Me 5 283 Ku, SMF 1828 ; Paratypes. Inner Gulf of Aden ; 12° 30.9N, 44° 47.7E; 76m, 06.03.1987, Meteor Station Me 5 283 Ku, SMF 1934–1936

Other specimen examined: Adeonella polystomella , West Africa, Atlantide expedition, without station number; Adeonella pallassi, Ionian Sea, Sivota , 39° 24N, 20° 14E; 1979, SMF unregistered; Adeonella pallassi, Aegaean Sea, Astros, Cave , 37° 20N, 22° 47E; 1m, 1973, SMF unregistered

Etymology: Dedicated to Dr. Peter Hayward for his enourmous contributions to the overview of the genus Adeonella , including the descriptions of far more than the half of the 41 species. Furthermore his help as my supervisor and professional support is greatly appreciated.

Diagnosis: A. haywardii n. sp. is distinguished from other species in the genus by its paired peristomial avicularia, pointing proximo­medially, arising close to the proximal corners of the secondary orifice. The primary orifice is slightly longer than wide, with a broad, shallow sinus and no condyles.

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7 8 FIGURE 2: 1–2 Adeonella distenta . 1 group of autozooids; 2 secondary orifice; 3–8 Adeonella haywardii ; 3 Group of Autozooids; 4 single autozooid; 5 primary orifice; 6 secondary orifice; 7 avicularia; 8 distal cut through the colony.

Description: Colony forming a branched, three­dimensional form 40mm high. Branches broadening distally, up to 15mm wide, with 5–7 longitudinal series of autozooids on each face. Autozooids oval to hexagonal (0.43– 0.65 x 0.20–0.30mm), rounded distally; separated by distinct grooves; sometimes without this group to the adjacent lateral zooid. Frontal wall convex, with small closely spaced pores. Spiramen round (0.03–0.05 x 0.03– 0.06mm). Primary orifice slightly longer than wide, with a broad, shallow sinus and no condyles. Secondary orifice (0.07–0.10 x 0.008 –0.011 mm) at first semi­circular, later almost circular, with 4 denticles on the proximal side. Peristomial avicularia typically paired, very rarely single or wanting, arising close to the proximal corners of the secondary orifice, usually pointing proximo­medially, mandible short, elongate triangular. One single proximal frontal avicularium was observed. In later ontogeny, conical umbones typically present proximal or/and paired just lateral to peristomial avicularia. Marginal autozoids tend to be longer than those of the median series, but are otherwise identical to them. Vicarious avicularia absent.

Remarks: There are similarities with A. polystomella , which has been reported from the coasts of West Africa, from Mauritania (Canu & Bassler 1828), to Angola ( Redier & d’Hondt 1976; Cook 1985). Yet the new species has got longer avicularia which are directed proximo­medially. A. pallasii , which has been frequently confused with A. polystomella (Hayward 1983, 1988) shows also proximo­medially directed avicularia and so does Adeonella sp. 1 (Hayward 1983) . A. polystomella and A. pallasii however bear Ushaped and A. sp. 1 a triangular sinus unlike the wide sinus of A. haywardii n. sp.