A revised description of nigra Baba, 1937,

type species of Alderiopsis, n. g.,

from Japan (-)

by

Kikutarô Baba

Biological Laboratory, Osaka Kyoiku University, Osaka, Japan

The form without formationof species nigra was originally reported by me true (produced

in (BABA, 1937) on a single specimen towed the head-corners may be horn-like, but they are flat, and

Zostera in Tomioka with with the of the zone Bay, Amakusa, a pre- not supplied extension rhinophorial

sumption that it belonged to Alderia Allman, 1846, nerves). Anus not terminal but situated at the right

the the With in general organization (depressed body-form anterior corner of pericardium. a single

and radula) of the . At the same time it was branchial row on both sides. Radular teeth smooth

noticed that differed from modesta Alderia. Stomach with nigra (Lovén, as in simple, not provided of of such char- diverticula. 1844), type the genus, in a series secondary A perdal stylet is present as

acters as the formation of the rhinophores, the ar- in Alderia. A distinct .

rangement of the branchial papillae, and especially Egg-masses flat band-like, and tend to be coiled. the non-terminal of the The real the leaves of in position anus. Living on Zostera.

situation of nigra in the systematics has been obliged Type: Alderia nigra Baba, 1937.

to remain unclarified until now.

Here I intend to refer to Dr. A. Inaba who kindly Alderiopsis nigra (Baba, 1937) afforded me with chances to re-discover specimens

of this in fair numbers from the Alderia 1-3. rare species among nigra Baba, 1937, pp. 249-251, text-figs.

— Tomioka, Amakusa. bushes of Zostera in the vicinity of the Mukaishima

The additional records of collecting are as follows: Marine Biological Station. Immediately after the Tannowa, Osaka Bay (Mar. 28, 1960, 10 sps.; Apr. 24, above the confirmed from finding species was by me Inland of 1960, many sps.); Mukaishima, Sea Seto (Mar.

above the leaves of this in Osaka 26 5 Mar. eel-grass Bay. By 4 and 16, 1960, sps.; Apr. 2, 1961, sps.; 22,

the obtained material before 1962, 25 Mar. 28, 1963, 27 Mar. 28, 16 examining newly me, sps.; sps.; 1967, sps.). I have been led to point out additional differences between nigra and modesta in the habitats, in the The external features of the checked under body were and several of the internal egg-masses, in points ana- binocular live a microscope mostly on specimens tomy. Establishment of a new taxon of generic rank taken from the sea. For the examination of internal thus to be for the sake of the appeared necessary listed below in organs 9 specimens were prepared former species (cf. MARCUS & MARCUS, 1956, p. 16; serial sections stained with Delafield's haematoxylin 1955, HAND & STEINBERG, p. 26). and eosin: This to dedicate to Prof. paper was prepared it Sp. Nos. 1-2. Mukaishima, Mar. 16, 1960. (H.S.) Dr. H. Engel of the Zoological Museum, University Sp. No. 3. Mukaishima, Apr. 2, 1961. (H.S.) of Amsterdam, with the hope to recognize the inter- Sp. Nos. 4-6. Mukaishima, Mar. 28, 1963. (H.S.) esting information given by his and his collaborators' Sp. No. 7. Mukaishima, Apr. 2, 1961. (L.S.) work of 1940 on from the coast line Sp. Nos. 8-9. Mukaishima, Mar. 16, 1960. (T.S.) of The Netherlands.

and EXTERNALS: The general body-form colours are Alderiopsis n. g. approximately as noted previously (BABA, 1937) save Somewhat allied to Alderia in the depressed body- the of which is shown here in position anus as being

front of (not behind) the and *) Contributions from the Mukaishima Marine Biological pericardium, slightlv the of the median line. The lies Station, No. 89. to right nephroproct 6 K. BABA

behind the To the of the forms distal vestibulum. show closely anus. right anus a roomy Serial sections

there is small of the melanin black vesicle. that this vestibular is and not in a opening part closed, open The head rather and extensible. The head- with the the is large, communication vaginal cleft of over-

corners when greatly produced may assume the ap- lying body integument. Similarly closed vagina was

found also in pearance of paired rhinophores but actually they are the so-called dendritica (Alder flat and not provided with the extension of the rhino- & Hancock) and boodleae Baba, respectively

phorial nerves. The genital openings consist of a (private observation). Branches of the albumen glands

male oviducal and cleft included branchial The orifice, an orifice, a vaginal are not within the papillae.

which does not into the inner has curved pass directly vaginal penis a stylet.

lumen. Fusiform branchial papillae are set in a single

both sides. each row on They contain a longitudinal ECOLOGY: In its habitat A. nigra differs greatly from unbranched liver-diverticulum. The is short, body A. modesta (cf. Alder & Hancock, 1854; Engel,

and the foot has an typically depressed, expanded Geerts & Altena, 1940; Hand & Steinberg, 1955; flat sole. The of the matured is 2-3 length and others). That is, in the field the animals of A. The of the is mm. general ground-colour integument of nigra were found sitting on the leaves Zostera by almost the whole surface of slightly ashy-yellow, but their flat sole. feed this Presumably they on grass the back and sides covered with head, are thickly action though actual feeding of radular teeth could melanin black pigment. The head-horns produced not be secured under a binocular examination. They

including the eye-regions are whitish. Each of the the leaves. The of A. spawn on Zostera egg-mass branchial is white at the The papillae opaque tip. of flat band nigra consists a (not sausage-shaped as anal forms whitish circle. The sole is region a faintly tends in A. modesta) which to coil. The ovum, about darkcoloured. in diameter, white. takes 75 fi is opaque Copulation

place very often between two individuals in usual internals: The general shape of the radular teeth is reciprocal positions. During copulation the penis pro- The stomach forms as before (Baba, 1937). figured trudes in and into the great length, passes partner's which a simple organ passes laterally into a right cleft. lasts for while. After this vaginal Pairing a and a left liver No other diverti- system. secondary sexual the act penis is withdrawn, and a stream of cula found the of the stomach are on periphery in be from the of the sperms can seen flowing out tip A. EVANS, 1953, 255-256. median nigra (cf. pp. stylet. As the vaginal vestibulum is closed, it appears and diverticula in A. modesta). Within each pedal reasonable that to mention a hypodermic injection of the papillae the liver-diverticulum is short and into this vestibulum has occurred at the moment of unbranched. The intestine is short. It rises up to the copulation in the depth of the vaginal cleft. A hypo- anterior anus which opens at the right corner of the dermic injection at random was reported precisely by pericardium. No anal papilla is formed. Within the Hand & Steinberg (1955) for A. modesta, and REID there distinct heart heart absent pericardium is a (a is (1964) for Elysia maoria (see also notes by ENGEL, in A. modesta; cf. Engel, Geerts & Altena, 1940, GEERTS & ALTENA (1940) for Limapontia and Alde- 20; Evans, 1953, 251; it is missing also in A. p. p. When irritated the animals usual ria). emit as a milky uda; cf. Marcus & Marcus, 1956, p. 10). The kidney white fluid from the surface of the body. The bran- is an sac which takes a median dorsal posi- elongated of chial papillae which are deciduous are capable in the haemocoele. the central tion In nervous sys- to in being regenerated. They appear increase num- tem the visceral ganglion is fused with the infra- ber with the growth of the body. intestinal one (cf. A. uda; MARCUS & MARCUS, 1956,

The do not to p. 11). rhinophorial nerves appear pass SYSTEMATIC NOTES forth into the head-horns. The gonad consists of a

number of It is suggested here to place Alderiopsis in the large hermaphroditic follicles. The am- prox- of Alderia. A tentative of the pulla is thick, and winding. The palliai gonoduct imity arrangement spe-

cies of these two will be shown below: assumes a complete triaulic structure which relates genera

most closely to that of Limapontia (cf. GHISELIN,

338, 354, is Alderiidae Pruvot-Fol, 1954. 1966, pp. fig. SE). It accompanied by a Family spherical spermatheca ( bursa copulatrix) which is Rhinophores obsolete; body broad, and depressed. absent the known Alderia Alderia 1937. in type of (cf. GHISELIN, A. Alderiopsis n.g. Type: nigra Baba,

354, The which functions — Amakusa. Anus corner of 1966, p. fig. SF). vagina at right anterior pericar-

dium. A of branchial both sides. partly as a spermatocyst (= receptaculum seminis) single row papillae on