Armina paucifoliata, BABA, 1955

Gosliner, Terrence M. & Fahey, Shireen J., 2011, Previously undocumented diversity and abundance of cryptic species: a phylogenetic analysis of Indo-Pacific Arminidae Rafinesque, 1814 (Mollusca: Nudibranchia) with descriptions of 20 new species of Dermatobranchus, Zoological Journal of the Linnean Society 161 (2), pp. 245-356 : 256-259

publication ID	https://doi.org/ 10.1111/j.1096-3642.2010.00649.x
persistent identifier	https://treatment.plazi.org/id/761B2D60-487D-E25F-0951-FB0FFDC03D3E
treatment provided by	Valdenar
scientific name	Armina paucifoliata
status

Treatment

ARMINA PAUCIFOLIATA BABA, 1955 View in CoL ( FIGS 1B View Figure 1 , 4 View Figure 4 , 5 View Figure 5 )

Armina paucifoliata Baba, 1955: 23 View in CoL , text figures 32– 33, pl. 11 figure 31.

Material examined: CASIZ 171415 , two specimens, one dissected, 33 mm, 50 mm alive, between Panglao and Pamilacan Islands, 9°33.4′N, 123°51.0′E, fine sand and mud with echinoderms, stn GoogleMaps T27 , 106– 137 m depth, collected 25.vi.2004 by T. Gosliner , Y. Camacho, J. Templado, M. Malaquias, M. Poddubetskaia . CASIZ 174128 , OT 607, three specimens 55–90 mm alive, off San Isidro , Panglao Island Philippines, 9°33.4′N, 123°49.6′E – 9°33.8′N, 123°51.5′E, mud and fine sand, stn GoogleMaps T10 117–124 m depth, collected 15.vi.2004 by T. Gosliner , Y. Camacho, J. Templado, M. Malaquias, M. Poddubetskaia .

Geographical distribution: This species is known only from Japan ( Baba, 1955) and Panglao, Philippine Islands (present study).

External morphology: The body shape of the living animal ( Fig. 1B View Figure 1 ) is broad, flattened, and narrows at the posterior end. The wide foot projects beyond the distinct mantle margin. The posterioventral end of the foot of the larger specimens has a narrow elongate pedal gland that is one-quarter to one-third of the total body length. There are up to 15 prominent longitudinal dorsal ridges with some additional Buccal armature: The jaws are large and thickly cuticularized ( Fig. 4A View Figure 4 ), with a thick masticatory margin and multiple rows of pointed denticles along the entire margin ( Fig. 4B View Figure 4 ). The radular formula is 31 ¥ 15.28.1.1.1.28.15. The rachidian teeth ( Fig. 4C, D View Figure 4 ) are broad with a large, spear-shaped central cusp and five to seven flanking denticles on each side. The flanking denticles are all the same thickness. The narrow, posteriorly directed first lateral tooth has six blunt denticles and a broad base with a ‘beak’ on the inner side. The next 27 lateral teeth ( Fig. 4E View Figure 4 ) are hook-shaped with up to nine denticles on the outer side that decrease in size and number towards the outer edge of the radula. The next 15 lateral teeth are also hook-shaped, with no denticles. The outer two teeth are smaller than the other teeth ( Fig. 4F View Figure 4 ).

shorter ridges in between, on the dorsal surface of the notum. The distinct anvil-shaped oral veil extends well forward and is laterally pointed. Behind the oral veil are the closely spaced rhinophores. The rhinophores have a series of longitudinal lamellae on the rounded club. The stalk widens as it enters the dorsal cavity and there are no lamellae on the stalk. A caruncle is situated just posterior to the rhinophores. Marginal sacs are not visible along the mantle edge. Under the mantle there are at least 25–40 small, weakly formed branchial folds at the anterior end of the body and approximately 50 wavy rows of complete and incomplete hyponotal lamellae at the posterior end. The genital opening is situated in the anterior third of the body wall and the anus opening is approximately half way along the body.

The ground colour of the dorsum and foot is deep brown or black and the dorsal ridge crests are pale yellow to opaque white. The mantle edge is opaque white or pale yellow. The rhinophores are black. The ventral side of the oral veil and the foot sole has dark speckles and the edge of both is opaque white.

Reproductive system: The reproductive organ arrangement is androdiaulic. The long hermaphroditic duct leads from the ovotestis into the tubular ampulla ( Fig. 5 View Figure 5 ). The ampulla bifurcates near the distal end of the female gland mass into the well-defined albumen gland and into the very long, multi-coiled prostate. The prostate expands into the long penial sheath. The penis is thin and elongate and rounded at its apex. From the large, ovoid bursa copulatrix the narrow vaginal duct emerges and continues to a narrow vagina that exits adjacent to the penial opening.

Remarks: Armina paucifoliata was described from a single specimen collected from Sagami Bay, Japan. The external morphology, radula, and jaws were described, but the reproductive system was not. The colour pattern between the Japanese specimen and the present material is entirely consistent. In the figure of Baba’s preserved animal ( Baba, 1955: text fig. 32), the elongate pedal gland and the thin, elongate penis are visible and are consistent with the form in the present material. The rachidian teeth of the Japanese and present material have five to seven denticles that extend well onto the median cusp. The other radular teeth are very similar in their denticulation in specimens from both localities with the following exception: the material from the Philippines has up to nine denticles whereas the Japanese specimen based on the figure ( Baba, 1955: text fig. 33B) appears to have fewer. The differences between Baba’s specimen and the present material are relatively minor and there is little doubt that they are conspecific.

Externally, A. paucifoliata closely resembles A. californica ( Cooper, 1863) and A. magna . All species have a very dark background colour and light coloured dorsal ridge crests and mantle margin. The white mantle edge of A. californica is much wider with more solid pigmentation than the narrow, uneven white pigment along the edge of A. paucifoliata . Armina magna has a yellow to orange mantle edge. For a complete comparison between A. magna and A. paucifoliata , see the Remarks section of A. magna .

Comparison between A. paucifoliata and A. californica

The oral veil is very different between these two species. The veil of A. paucifoliata is anvil-shaped and has a smooth margin. The veil of A. californica is rounded and has a scalloped edge. The pedal gland of A. californica , although elongate, is much shorter than that of A. paucifoliata . The anterior branchial folds are much more well-developed in A. californica than in A. paucifoliata .

The two species have similarities in their radular morphology. Both have a broad, denticulate rachidian tooth with a longer central cusp. Both have denticulate lateral teeth and some smooth outer teeth. The radular formula of A. paucifoliata is 31 ¥ 1 5.28.1.28.15 but that of A. californica is 41 ¥ 60.1.1.1.60. Marcus (1961) noted that only the outermost six lateral teeth are smooth in A. californica whereas the outer 15 lateral teeth are smooth in A. paucifoliata . In A. californica , the central cusp of the rachidian tooth is about as wide as the adjacent denticles and the denticles extend almost to the tip of the apex of the central cusp. In A. paucifoliata , the central cusp is much broader than the denticles and the cusp extends well beyond the denticles. The inner lateral tooth of A. californica is much shorter than that of A. paucifoliata . The denticles on the lateral teeth of A. californica are isolated to the tips of the teeth whereas the denticles on the lateral teeth of A. paucifoliata are numerous and are lined up on the outer side of each tooth.

The reproductive morphology of these two species has similarities. Both have a long, coiled prostate and an enlarged penial sheath, but A. californica has a much more bulbous sheath. The vaginal duct of A. californica is short and the vagina is large and bulbous. In contrast, the vaginal duct of A. paucifoliata is long and narrow, as is the vagina as it enters the genital atrium. The penis of A. californica is unusual in that it is highly coiled whereas that of A. paucifoliata is thin and straight.