A new species of Pentamera Ayres, 1852 from the Brazilian coast (Holothuroidea, Dendrochirotida, Phyllophoridae)

Abstract Pentamera paraibanensis sp. n. is described from more than 3000 specimens as a new species of Phyllophoridae from northeast Brazil, in the tropical southwestern Atlantic. It is distinguished from its congeners by the shape of the calcareous ring with moderate posterior processes, and by the tables in the body wall with a usually quadrilocular disc and a low, toothed spire composed of two pillars. The body is brown, with the tube feet in double rows per ambulacrum, and tentacles more lightly colored. The species was found inside rodoliths in large numbers. This paper contains a morphological description of the specimens, and an account of their habitat characteristics.


Introduction
The order Dendrochirotida contains most of the world's described holothuroids. In Brazilian waters, it is represented by the families Psolidae, Cucumariidae, Sclerodactylidae and Phyllophoridae (Tommasi 1974, Tommasi et al. 1988a, b, Martins et al. 2012, Ventura et al. 2012. Phyllophoridae (sensu Pawson and Fell 1965) have 10 to 25 tentacles, with tube feet scattered over the entire body or restricted to the radii and a calcareous ring complex with usually radial plates of medium to large size, subdivided into several pieces (Thandar 1990). Östergren (1907) considered phyllophorids as a subfamily within the Cucumariidae, based on the arrangement of the tentacles. Later, Heding and Panning (1954) revised the family Phyllophoridae, which they subdivided into several subfamilies. Pawson and Fell (1965) regrouped the families of Dendrochirotida based on the shape of calcareous ring (simple or complex) and tentacle number. That review included within the Phyllophoridae the subfamilies Phyllophorinae, Semperiellinae and Thyoninae. Recently Smirnov (2012) considered Thyoninae as differing from other Phyllophoridae on the basis of the number of tentacles and the morphology of the calcareous ring complex. He raised its rank to family level. Several changes in the taxonomy of the Holothuroidea occurred through time, mainly in Dendrochirotida. However, many questions still remain unresolved until now. As more knowledge is produced, answers to some of these open questions will be provided. Ayres (1852) erected the genus Pentamera to accommodate species with oval body, with tube feet in the radii and ossicles of the body wall that are smaller than those present in Thyonidium Düben & Koren, 1846. Pentamera includes 19 species, most from the Pacific Ocean. In the Western Atlantic only the type species Pentamera pulcherrima Ayres, 1852 was hitherto recorded. Species of Pentamera are generally of small size with tube feet restricted to the radii and calcareous ring with moderate to long posterior processes and tables from body wall composed of two pillars (Cherbonnier 1951).
Numerous specimens associated with rodholiths from the coast of Paraíba, northeast Brazil, represent a new species.

UFPB.ECH Echinodermata Collection of Federal University of Paraiba UFSITAB
Echinodermata Collection from Federal University of Sergipe

Material and methods
The examined material is deposited in the Collection of Invertebrates Paulo Young, of the Department of Systematics and Ecology, Federal University of Paraíba (CIPY/ DSE-UFPB), and in the Echinodermata Collection, of the Department of Biosciences, Federal University of Sergipe, Brazil. The methods used to study the specimens followed , Pawson et al. (2010), and Thandar (1989). Tissue fragments for the extraction of ossicles were immersed in a 3% solution of sodium hypochlorite, washed five times in distilled water, and rinsed with absolute ethanol. Permanent slides were prepared and were studied by light microscope. Other samples were dried and mounted on metal stubs, coated with gold and observed with FEI Quanta 200F scanning electron microscope. Photographs of specimens were taken using a Canon Powershot A2000IS digital camera, and a Leica MZ12.5 stereomicroscope. Measurements were obtained from fixed specimens.

Systematics
Order Dendrochirotida Grube, 1840 Family Phyllophoridae Östergren, 1907 Subfamily Thyoninae Panning, 1949 Genus Pentamera Ayres, 1852 Diagnosis. Small to medium sized. Ten tentacles, with two ventral ones smaller. Tube feet only in the radii, elongated, slightly retractile. Calcareous ring with moderate to long posterior processes. Body wall with tables of two pillars or derivatives of these, sometimes accompanied by plates. Tube feet with large endplates and curved supporting tables varying from low to high spire. Tentacles with rods, plates or rosettes (modified after Deichmann 1941, Lambert 1998).
Remarks. The diagnosis has been modified to include the new species and the fact that the type and some other species have plates in the body wall in addition to tables. Pentamera paraibanensis sp. n. has posterior processes of medium size and rosettes in the tentacles. Diagnosis. Small body, reaching 7 mm, anterior and posterior ends slightly upturned. Color brown in life and in alcohol, tube feet light brown to white. Tube feet only in the radii. Tentacles ten, branched, two ventral ones smaller. Skin thin, smooth. Body wall ossicles comprise oval tables (with disc up to 64 µm long) with four central holes, sometimes more elongated and also with smaller holes marginally and smooth multilocular plates; spire low, with two short pillars ending in 2-3 blunt teeth. Tube feet with supporting plates, curved support tables of variable height, and endplates. Tentacles with rosettes and rods. Introvert with rosettes.
Etymology. The species epithet is derived from the name of the State where it was collected (Paraíba State, Brazil).
Description of holotype. Specimen (female) small, globiform, slightly curved, length along the body 7 mm and breadth in mid-body 3 mm ( Figure 1A, B, C). Preserved coloration brown, podia and tentacles light brown to white. Mouth upturned; anus terminal with five small papillae and five delicate anal teeth ( Figure 3J). Tentacles extended, ten, well-branched, largest about 1.5-2 mm long, two ventral ones smaller. Tube feet restricted to radii, in double rows, longer in the ventral radii, shorter dorsally. Interambulacra usually naked, without papillae, warts or tubercles. Skin smooth, slightly translucid, with numerous small ossicles. Introvert thin, short, without tube feet.
Calcareous ring complex, not fragmented, with posterior processes elongated (Figure 1G). Radial plates longer than interradial, approximately 2 mm high and 0.5 mm wide, anterior part bifid, posterior processes with small pieces; interradial plates triangular anteriorly, with posterior margin convex, 1.3 mm high and 0.3 mm wide. Polian vesicle single, short, saccular, located slightly to left of ventral mesentery; stone canal thin, straight, elongated; madreporite well calcified, bean-shaped. Gonads in one tuft of several tubules attached anteriorly, unbranched but forming several saccules along the tubule, filling the entire body cavity, full of eggs in various stages of development. Longitudinal muscles thin; retractors also thin, more delicate. Respiratory trees confined to posterior quarter of body, with short branches.
Characteristic ossicles of body wall as oval tables with disc of usually four perforations and a low spire of two pillars ( Figures 1I and 2D and H), 50-70 µm long and 20-30 µm high, ending in 2-3 teeth. Other body wall ossicles include some irregular smooth plates ( Figure 3G). Tube feet ossicles of three types, supporting tables with curved disc with four central holes and 1-3 holes at ends, disc 128 µm long and spire 30 µm high (Figures 1J; 2F-G, and 3B-F). Elongate perforated plates, 99 µm long and 40 µm wide ( Figure 2E and 3A), and rounded endplates with central perforations smaller than others, about 170 µm in diameter ( Figure 3H-I). Some large plates also occur near the podia ( Figure 2I). Introvert with rosettes only ( Figure 2C). Tentacles with rods of various sizes, some delicate, with perforations at each end, some curved, others with four arms; irregular perforated plates, oblong, straight to slightly curved, medial perforations larger ( Figure 2B) and rosettes similar to those of introvert ( Figure 1H, 2A).
Morphometry. (See Table 1 below). Rosettes of tentacles are larger than those of introvert. In general, ossicles from dorsal surface larger than those from ventral surface.  Figure 3. Pentamera paraibanensis sp. n. A Support plates from ventral body wall B Base of support tables from ventral tube feet C Curved base of support tables from ventral tube feet D Support plate of tube feet E Support tables from ventral tube feet F Curved support tables from ventral tube feet G Large plate from body wall near the anus H Endplate from dorsal tube feet I Endplate from ventral tube feet J Anal tooth.
Dorsally, tables of anterior region are larger than of posterior region but their spire is lower. Endplates are also larger anteriorly. Supporting tables of the podia are smaller in posterior region, but are wider and higher anteriorly. On ventral surface, the tables from anterior part are slightly larger than posteriorly. Endplates of the postero-ventral surface are larger than the anterodorsal surface, about 140 µm in diameter. The supporting tables are slightly larger and taller anteriorly, but wider posteriorly (108.08 × 26.51 × 17.47 µm). The supporting plates from the posterior region are larger, approx. 103 µm.
Description of paratypes. The paratypes are from 0.4 to 1 cm long. The ossicles of the body wall and other parts of the body are similar. Some tables are more elongated or have more than four perforations. The color varies from light to dark brown. Some specimens have their body dark brown and their tube feet light brown (Figures 1D-F).

Color variations.
A total of 3225 specimens was examined, measuring 3-13 mm long and 3-3.5 mm wide in the mid part, and 1-2.5 mm at the ends were examined. In general, they all present a curved form, but some specimens are elongated or only slightly curved. The body wall is dark to light brown in color, sometimes with dark spots, the tube feet varying from whitish to yellowish, and the tentacles with translucent peduncles and brown to yellow branches. Most specimens present a brown coloration, with some dark brown spots and whitish tube feet.
Habitat. Most specimens were inside rhodoliths, but some samples were associated with Halimeda sp., were part of the phytal of Hypneia sp., or came from a rocky bottom.
Remarks. The new species seems to shed the calcareous ring when submitted to stress. Some specimens were without the tentacles and calcareous ring, and most of them presented tentacles and the calcareous ring totally extended outside the body. This seems a defense tactic of this animal. The specimens studied agree with the diagnosis of genus Pentamera as amended by Lambert (1998). They share the structure of the calcareous ring and the type of body wall ossicles with other species currently classified in the genus Pentamera. Pentamera paraibanensis sp. n. with its double row of tube feet, body wall with tables with two pillars, and with the shape of the supporting tables and endplates, has parallels with other species of the genus. Pentamera paraibanensis sp. n. has similar tables as those of Pentamera pediparva and Pentamera constricta, but differs from both in the moderate calcareous ring, height of spire of supporting tables of tube feet, presence of rods and rosettes in tentacles and only rosettes in the introvert. In addition, these species have stiff and rough skin, while P. paraibanensis sp. n. has soft and smooth skin. We also compared the new species with other species of the genus Pentamera, as well as with other species of Phyllophoridae reported from the South Atlantic directly or through specialized literature (e.g., Cherbonnier (1951), Deichmann (1930Deichmann ( , 1938Deichmann ( , 1941, Lambert (1998), andTommasi (1969).
The new species P. paraibanensis sp. n. differs of Pentamera beebei Deichmann, 1938 andPentamera zacae Deichmann, 1938 by the absence of high pillars of the body wall tables; from Pentamera chierchiae (Ludwig, 1887) by the absence of rods in the introvert and tables with spinous disc; from Pentamera chiloensis (Ludwig, 1887) by the absence of quadrangular base of tables from the body wall, with pillars ending in several teeth; from Pentamera calcigera Stimpson, 1851 it can be distinguished by the absence of a dense layer of plates and by the form of the tables from the body wall; from Pentamera charlottae Deichmann, 1938 by the absence of small tables from the body wall; from Pentamera lissoplaca (Clark, 1924) by the absence of diamond-shaped tables and diminutive tables in the body wall. P. paraibanensis sp. n. differs from Pentamera trachyplaca (Clark, 1924) by the absence of thick oval knobbed plates; from Pentamera pseudocalcigera Deichmann, 1938 by the absence of star-shaped plates in the body wall; and from Pentamera rigida Lambert, 1998 it may be clearly distinguished by absence of large thick tables, knobbed plates in introvert and the shape of the calcareous ring.