Sacculina quadrialata, Boyko & Van Der Meij, 2018

SACCULINA QUADRIALATA SP. NOV.

( FIGS 9, 12A, B)

urn:lsid:zoobank.org:act:A646BB1F-4BA5-46EE-96C1-AF7A4BDE1FCB

Type material

Indonesia: mature holotype externa (1.6 mm long × 1.2 mm wide) (RMNH.Crus.C.10250), ex abdomen of feminized male Opecarcinus sp. 1 (F) (3.0 mm long × 2.3 mm wide) (RMNH.Crus.D.53990), ex L. mycetoseroides Wells, 1954 ( Agariciidae ), South Pilongga, Tidore, 00°42′44″N, 127°28′47″E, 12 November 2009, coll. S. E. T. van der Meij; two mature paratype externae (2.0 mm long × 3.4 mm wide, 1.4 mm long × 2.0 mm wide) (RMNH.Crus.C.10251), ex abdomen of female Fizesereneia heimi ( Fize & Serène, 1956a) (5.3mmlong×4.5mmwide)(RMNH.Crus.D.54018), ex Lobophyllia cf. radians (H. Milne Edwards & Haime, 1849) (Lobophyliidae), Tanjung Sidangolo, Halmahera, 00°53′40″N, 127°29′28″E, 5 November 2009, coll. S. E.T.van der Meij; mature paratype externa (1.4 mm long × 1.9 mm wide) (RMNH.Crus.C.10252), ex abdomen of feminized male Lithoscaptus cf. bani ( Fize & Serène, 1957) (3.1 mm long × 2.0 mm wide) (RMNH.Crus.D.53993), ex Goniastrea edwardsi Chevalier, 1971 ( Merulinidae ), West Mansuar, Raja Ampat, 00°30′41″S, 130°33′35″E, 9 December 2007, coll. S. E. T. van der Meij; immature paratype externa (0.7 mm long × 1.0 mm wide) (RMNH.Crus.C.10253), ex abdomen of female Opecarcinus cf. sierra Kropp, 1989 (1.9 mm long × 1.4 mm wide) (RMNH.Crus.D.54208), ex Pavona cf. varians Verrill, 1864 ( Agariciidae ), North Tanjung Pandean, Lembeh Strait, 01°24′21″N, 125°10′04″E, 14 February 2012, coll. S. E. T. van der Meij; mature paratype externa (0.8 mm long × 1.1 mm wide) (RMNH.Crus.C.10254), ex abdomen of female X. sheni ( Fize & Serène, 1956b) (1.9 mm long × 1.3 mm wide) (RMNH.Crus.D.54166), ex M. elephantotus ( Pallas, 1766) ( Merulinidae ), Tanjung Labuhankompeni, Lembeh Strait, 01°25′55″N, 125°11′10″E, 4 February 2012, coll. S. E. T. van der Meij.

Description

Externa of immature specimens with rounded subequal lateral lobes; mature (ovigerous) externae with lateral lobes produced anteriorly and posteriorly into wing-like extensions, sometimes subequal but often of differing degrees of extension. Mantle opening mediodistally located opposite stalk. Mantle opening ranging from smooth to crenulated, raised off the surface of the externa. Stalk short but externa raised off the surface of the host abdomen. Cuticle with varying degrees of wrinkling, particularly prominent in larger specimens.

Etymology

The species name alludes to the four wing-like lobes (quadri + alata) of the mature externa.

Remarks Vervoort(inMartin&Davis,2001)statedthat‘Sacculinidae must be ascribed to Lilljeborg (1860)’. However, nowhere in Martin & Davis (2001) was the actual bibliographic reference to Lilljeborg, ‘1860’ given. After careful analysis of all the publications of Lilljeborg dealing with rhizocephalans, we must conclude that the date was given incorrectly by Vervoort, and is, in fact, Lilljeborg (1861).

Although it would be desirable to perform histology on at least some of these specimens, the hosts were not preserved with rhizocephalan histology in mind, and it is doubtful that any internal characters can be gleaned from such treatment. Additionally, the utility of many of Boschma’s internal characters in terms of showing evolutionary relationships has yet to be demonstrated; some of these characters may be homoplasies, but this remains to be tested. Rybakov & Høeg (2002) showed the utility of studying the retinacula found on the mantle of externae, but there are no such structures in this new species nor are they known in many of the species of Sacculina . However, this new species can be described and named because the presence of the four laterally extended wing-like lobes on the mature externae is unlike the externae shapes seen in other species of Sacculina . The most similar species to this new species is S. rugosa Van Kampen & Boschma, 1925 , but the shapes of the externae are only vaguely similar. Additionally, there are no previous records of any rhizocephalans from gall crab hosts.

Known hosts

Opecarcinus sp. 1 (F) (type host), F. heimi ( Fize & Serène, 1956a) View in CoL , Lithoscaptus cf. bani ( Fize & Serène, 1957) View in CoL , Opecarcinus cf. sierra Kropp, 1989 View in CoL , X. sheni ( Fize & Serène, 1956b) View in CoL .

Distribution

Known only from Indonesia.