A new species of the zephyrinid nudibranch genus Janolus ( Mollusca : Nudibranchia ) from North America and Costa Rica

A new species of zephyrinid nudibranch of the genus Janolus Bergh 1884 is described from the Pacific Coast of North America and Costa Rica. J. anulatus sp. nov. differs from other species of Janolus by its external and internal morphology. J. anulatus has a brown or white body with pink, white, and brown spots, smooth papillae epithelium at the base and papillated in the distal part, unbranched digestive gland ducts, smooth jaws, and smooth rachidian and lateral teeth. The species is compared with other species from the Panamic Province and the Western Atlantic. A new extension range of J. barbarensis is documented. Rev. Biol. Trop. 54(4): 1295-1305. Epub 2006 Dec. 15.

Geographic range: This species is known from La Jolla, California (Behrens 1991) and the Pacific Coast of Costa Rica (present study).
Etymology: The name of the species "anulatus" refers to a ring that is found near the middle of each dorsal papilla that separates the smooth from the papillate portion.

External morphology:
The body is broadest anteriorly, tapering to the acute posterior end of the foot.The rhinophores are perfoliate with about 10 complete or incomplete transverse lamellae.There is a small, convoluted inter-rhinophoral crest (caruncle) between the rhinophores (Fig 2A).The large, bulging cardiac area is located near the middle of the notum.A pair of short, broad, digitiform oral tentacles extends from either side of the head.The dorsal papillae are stout and cup-shaped with a long prolongation at the apex.The base of each papilla is smooth, followed by a ring and numerous small papillae that extend the length of each papilla (Fig 2C).The papillae are arranged in two longitudinal rows of up to 25 papillae.The digestive gland inserts into the papillae at a point just below or just above the ring of the papilla.The digestive gland does not branch.The anus is located mid-dorsally near the posterior end of the dorsum (Fig 2D).A large anal gland is present below the anus.The gonopore is located on the right side in the middle of the body, while the nephroproct is situated more posteriorly.
In some specimens, the background color of the dorsum bears two colors: the anterior half dark brown, the posterior half light brown.In others, the background color is white with some brown spots (Fig 1A).Around the eyes, there is a translucent light cream mask.A pink spot extends from behind the rhinophores to the anterior part of the cardiac area.There is another pink spot in front of the rhinophores with two opaque white spots to the sides.The cardiac area is opaque white in color.The anus is opaque white with a small stalk.Rhinophores are dark cream with light apices and some central dark brown spots.The inter-rhinophoral crest is opaque white with a few cream spots.
The digestive gland within the papillae is chocolate brown.The background color of the papillae is light cream with some large brown and opaque white spots.The smaller papillae on the digestive gland are yellow.There are some green reflective specks distributed homogenously on the body.Dorsally, the foot is translucent with very small cream-colored spots around the margins.Ventrally, the mouth has numerous light brown specks, the oral tentacles are opaque white, and the foot bears cream specks.

Anatomy:
The buccal mass is large and muscular with an oval opening and with small anterior oral glands in front of it (Fig. 3A).The strong jaws are amber in color.They are joined together and are devoid of any serial denticles (Fig 3B,5D).The inner masticatory border is thick and smooth.
The radular formula is 13 x (19.1.19)in a 4 mm preserved length specimen.The rachidian teeth are small and somewhat amorphous in shape, without denticles (Fig. 5A).The inner lateral teeth are hook shaped, smooth, and arched (Fig. 5B).They gradually become larger from the innermost to the mid-laterals, then become smaller from the mid-laterals to the hook-shaped outermost teeth (Fig 5C).
The ampulla is thick and convoluted.It narrows into the bifurcation of the vas deferens and the thin oviduct.The distal vas deferens is short and enlarges into a much thicker, curved prostate.The prostate narrows into a convoluted ejaculatory duct that connects to the large, conical, unarmed penis (Fig 4).The oviduct is short and expands into a tubular serial seminal receptacle.This duct again narrows and widens into the muscular, kidney-shaped vagina.A tubular bursa copulatrix enters the female atrium near its junction with the oviduct.The female gland mass is oval and exits into the female atrium.
Remarks: J. anulatus sp.nov.differs from other species of the genus Janolus from the Panamic Province and the Western Atlantic in its internal and external morphology (Table 1).J. anulatus is characterized by having a brown or white body with pink, white, and brown spots, smooth papillae epithelium at the base and papillated in the distal part of each papilla, unbranched digestive gland ducts within the dorsal papilla, smooth jaws, and smooth rachidian and lateral teeth.Comparative morphology of the valid species of the genus Janolus from the Panamic Province and Western Atlantic J. barbarensis and J. costacubensis, two species present along the Pacific and Caribbean coasts of Costa Rica, respectively, differ from J. anulatus.J. barbarensis has a translucent white body with gold and blue cerata, markings on the dorsal papillae with branched digestive gland ducts, jaws with denticles, and lateral teeth with denticles.J. costacubensis has a cream body with a longitudinal white line, rhinophores with papillae on the bases, and lamellae in the distal part of the rhinophores.In this species, the entire epithelium of the dorsal papillae bears papillae, while in J. anulatus only the apical portion above the ring bears papillae.The digestive gland in the papillae of J. costacubensis extends for more of the length than does that of J. anulatus.
Of the six species of J. described from the Americas, only J. comis and J. costacubensis have dorsal papillae with a papillate rather than smooth surface.These two species, together white-tipped papilla.J. rebeccae externally resembles J. barbarensis but differs to some extent in internal morphology and radular features discussed in detail by Schrödl (1996).
J. chilensis Fischer, Cervera and Ortea 1997, another species described from Chile, is considered a junior synonym of J. rebeccae (Cervera 1997).However, Schrödl (2003) considered both species different due to differences in their reproductive system.More material from Chile needs to be examined.
J. hyalinus (Alder and Hancock 1854), a species present in the Atlantic and Mediterranean waters of Europe, also resembles J. anulatus because of the presence of papillae on the dorsal papillae.However, this species has many more dorsal papillae and these are more elongated and evenly shaped than those of J. anulatus, which has unevenly tapered papil-lae with more prominent tubercles.J. hyalinus also has a semiserial receptaculum seminis, while J. annulatus has a serial one and a distal bursa copulatrix, which is absent in J. hyalinus (Schmekel 1970).Material examined: West side of Isla Ballena, Parque Nacional Marino Ballena, Área de Conservación Osa, Puntarenas, Costa Rica (9°06'24" N, 83°43'35" W), 16 January 2000, 1 specimen, 4 mm preserved length, 6 meters depth, leg.M. Calderón (INB0001496134).

Janolus barbarensis
Geographic range: Central California to Bahía San Quintín, Baja California, the Gulf of California, México, and Costa Rica (present study).
Natural History: It has been found on the upper surface of rocks in 6 meters deep.

External morphology:
The body is broadest anteriorly, tapering to the acute posterior end of the foot.The rhinophores are smooth basally and perfoliate distally with about 13 complete or incomplete transverse lamellae.The inter-rhinophoral crest located between the rhinophores is hourglass shaped, and moderately convoluted (Fig 1D and 6A).A pair of short, broad, digitiform oral tentacles extends from either side of the head (Fig 6B).The smooth dorsal papillae are stout, wider in the middle, and have a short prolongation at the apex (Fig 2C).In the specimen examined, the papillae are arranged in about two rows on either side of the body, with two papillae per row.The digestive gland inserts into the papillae at the base and branches irregularly within the papilla.The anus is located mid-dorsally near the posterior end of the dorsum (Fig 6D).The large gonopore is located on the right side in the middle of the body.A large anal gland is present below the anus.
The living animal of the specimen examined is translucent orange with a number of small brown specks homogeneously distributed over the dorsum.The inter-rhinophoral crest is pinkish.The light brown greenish pigment of the digestive gland is visible within the cerata.The ceratal surface bears an orange-yellow subapical band and a bluish white apical band.The middle part of each rhinophore is light yellow with black spots; a number of minute brownish spots is located at the base of each rhinophore.The anus has a white ring around it.Dorsally, the foot is translucent white with a light blue line extending to the posterior end.Ventrally, the foot is light orange.

Anatomy:
The buccal mass is large and muscular with an oval opening and small anterior oral glands (Fig. 6E).The strong jaws are amber in color.They are joined together and have at least 7 strong and wide rectangular denticles around the masticatory border (Fig 7D).
The radular formula is 14 x (15.1.15)in a 4 mm preserved length specimen.The rachidian teeth are narrow with a pointed cusp, without denticles (Fig. 7A).The inner lateral teeth are hook shaped, smooth, and arched (Fig. 7B).They gradually become larger from the innermost to the mid-laterals, then become smaller from the mid-laterals to the hook-shaped outermost teeth (Fig 7C).
The reproductive system of the specimen was studied.However, some of the parts were not well developed because the specimen was immature.The ampulla is tubular and short.It narrows to the bifurcation of the vas deferens and oviduct.The vas deferens is short and convoluted.It narrows into a pear-like shaped penis (Fig 6F).The oviduct is short and expands into a tubular duct where the seminal receptacle is not clearly differentiated.This duct again narrows and widens into a globular bursa copulatrix and a globular vagina.The female gland mass is amorphous in shape and exits near into the female atrium.
Natural History: This species was found in the subtidal zone around 6 meters depth where it feeds on ramified bryozoans.

Remarks:
The internal and external morphology of the single specimen collected in Costa Rica perfectly fits with the description of J. barbarensis (Cooper 1863) in Gosliner (1982).Gosliner found and discussed in detail several consistent differences in the external morphology, coloration, digestive system and reproductive system that confirms that J. barbarensis is a distinct species from J. fuscus, another species found along the California coast.

TABLE 1
Comparative morphology of the valid species of the genus Janolus from the Panamic Province and Western Atlantic