Heterocyathus antoniae, Reyes & Santodomingo & Cairns, 2009

Reyes, Javier, Santodomingo, Nadiezhda & Cairns, Stephen, 2009, Caryophylliidae (Scleractinia) from the Colombian Caribbean, Zootaxa 2262 (1), pp. 1-39 : 27-29

Heterocyathus antoniae , new species

Figs. 4S–W

Description: Coralla subcylindrical. Holotype is 10 mm in GCD, 8.8 mm in LCD and 9.0 mm in height. Corallites initially settled on gastropod shells, which are overgrown during the coral development, and in some specimens the coral skeleton practically covered all the mollusc shell. The holotype base (8.1 x 10.6 mm in BD) displays five holes (sipunculid openings): four of them are aligned with the LCD at the middle part of the base (from the right to the left 0.8, 0.7, 0.2 and 0.6 mm in diameter), while the fifth one is located at the end of a conical shaped pipe (1 mm diameter) and it is projected out 2 mm and curved 30 from the thecal wall. Internal walls of the holes are covered by a thin, smooth and porcelain-like layer (0.2 mm thick). In the paratype specimen only two basal pores were observed. Some sabellid polychaete tubes are attached to the base in the holotype specimen. Base is covered by high, conical, almost cylindrical or bent granules perpendicularly oriented. Ridged costae equal in height and width, prominent. Coarse costal granulation develops from secondary accretion of a central rod-shape element, and flanked by two slender spines diagonally oriented against that central element. Lateral spines of C4 flank the C1-C2, and they are twice or three times higher than the external C4 spines. Intercostal furrows are deep and slender, sometimes with thecal pores connecting to the interior of the coralla. Calicular margin is lanceolated: S1 are the most exsert septa projecting up to 1.2 mm from the calicular margin adjacent to S3. Despite S1 are the most exsert septa, the distance from the thecal edge to the septal lobe is slightly longer for the S3 (S1 up to 1.2 mm, S2 up to 1 mm, S3 up to 1.3 mm). Septal ornamentation is twice to three times its respective septa width.

Septa hexamerally arranged up to five cycles, following a Pourtalès plan (S1=S2=S4>>S3); the fifth cycle incomplete, with two S5 associated to the principal axis. Septal axial edges are smooth and straight; deep and narrow palar notches extend just below the columella. S1 are the only independent septa, reaching the columella. Paliform lobes occur before all septa (P1 to P4), except for the additional S5; P4 composed of up to six palar teeth, gradually smaller while closer to the columella. P3 is composed of one or two lobes, twice the width of S1; P2 is twice to three times the width of P1, and P1 bearing three to four small lobes. Septacolumella junctions are fenestrated. The secondary accretion of septal ornamentation is connected by cylindrical synapticulae to the opposite septal-palar faces near the columella. Septal and palar granulation is laterally fused in carinae, perpendicular to the trabecular axis. Columella is spongy and elliptical (1.8 x 1.1 mm), composed of crispate elements, laterally fused. Fossa is shallow in the holotype, but deep in the paratype. Corallum present a white colour, but some specimens exhibit a brown or purple columella and septal bases.

Remarks: The genus Heterocyathus comprises 16 extant and 5 fossil nominal species ( Stolarski et al. 2001). The extant species were grouped into three valid species by Hoeksema & Best (1991): H. sulcatus ( Verrill, 1866) , H. aequicostatus M. Edwards & Haime, 1848 and H. alternatus Verrill, 1865 . However, Zibrowius (1998) and Cairns (1999b) suggest that a more detailed study should be performed in order to clarify the genus taxonomy. Following Hoeksema & Best (1991), Heterocyathus species are differentiated by the septal arrangement, lateral septal projection, and the coloration pattern: H. sulcatus is characterized by having a central part of the calices with dark brown or black colour, and short lateral septal projections; H. aequicostatus presents a compact corallum, white calices, long lateral septal projections and closely packed pali; and H. alternatus has spaced S1, white calices, and closely packed pali. Colombian Heterocyathus shares some characters with these three species: for instance, one paratype specimen (INV CNI2076) has a black columella and long lateral septal projections as H. sulcatus ; on the contrary, the holotype (INV CNI740) presents a completely white corallum, and spaced S1, showing a resemblance to H. alternatus . H. antoniae is also similar to H. alternatus in size (10 mm in GCD, sensu Cairns 1999b), and having a pointed costae granulation (USNM 90410, Indian Ocean, Burma, 80 m depth); but it differs from H. alternatus in the presence of additional pairs of S5 associated to the principal S1, a shallow fossa, slender and crispate columella elements, ridged lobe bases product of the palar granulation fusion, and by its subcylindrical coralla. H. aequicostatus (USNM 89955, Pacific Ocean, Philippines, 33 m depth) is similar to H. antoniae in its granular base and its costae extension up to the base edge; but, it is different in the corallum size and its low and rounded costae granulation. The characteristic of having extra pairs of S5 adjacent to the principal S1 system, is shared with H. japonicus ( Verrill, 1866) sensu Zibrowius (1998) , but they can be differentiated by the costal length; whilst in H. japonicus the costae extend until the base center of the corallum, in H. antoniae costae extend only to the base edge. H. antoniae resembles H. sulcatus (USNM 90079, Philippines, 33 m) because both species have subcylindrical coralla and similar calicular aspect, but H. antoniae present mainly white calices and equally wide costae. Thus, H. antoniae was established as a new species, based on its morphological characteristics and the particular geographic distribution restricted to the northern Caribbean coast of Colombia.

Distribution: Heterocyathus species are commonly found on sandy bottoms adjacent to coral reefs of the eastern Pacific and Indian oceans, from Japan to Mozambique ( Hoeksema & Best 1991; Cairns & Zibrowius 1997; Zibrowius 1998; Cairns 1999b). It is also known from the Gulf of California ( Durham & Barnard 1952). Heterocyathus species were only known as fossil for the Atlantic Ocean; the youngest record dates from the Miocene (20–15 MY, Burdigalian) and it was found at the southwestern France ( Stolarski et al. 2001). The particular distribution of Colombian specimens suggests that the species probably belongs to a relict fauna still present in the Caribbean. In Colombia, H. antoniae has been collected in the northeastern Caribbean coast, from Dibulla (La Guajira Peninsula) to Santa Marta; between 20 and 70 m depth.

Etymology: This species is named after the oldest daughter of J. Reyes, Antonia Reyes.

Material: Holotype, INV CNI740 , 1 specimen overgrowing a gastropod shell, 10 mm GCD, E118 , Colombia ( Santa Marta , Neguanje Bay) . Paratypes: INV CNI2076 , 1 specimen overgrowing a gastropod shell, 9.5 mm GCD, E237 , Colombia (La Guajira, off Manaure ) . Other material: INV CNI739 , 1 specimen settled on Polystira sp. shell, E105; INV CNI738 , 2 specimens settled on a juvenile Strombus sp. shell, E105 .

Figures

FIGURE 4. A, Lophelia pertusa, INV CNI396, off La Guajira (Honda Bay), colony fragments, x 1; B–C, Oxysmilia rotundifolia, INV CNI687, off San Bernardo Islands, calicular and lateral views, both x 1.1; D–E, Colangia immersa, INV CNI683, off La Guajira (Punta Gallinas), calicular and lateral views, both x 3; F–G, Phyllangia americana americana, INV CNI274, off La Guajira (Caricari Point), colony from calicular and oblique views, both x 2; H–I, Rhizosmilia maculata, INV CNI178, off Santa Marta, calicular and lateral views, both x 3.6; J–K, Phacelocyathus flos, INV CNI2940, off San Bernardo Islands, calicular and lateral views, both x 3.6; L–M, Anomocora fecunda INV CNI2897 off San Bernardo Islands, calicular and lateral views, x 3.2, x 1, respectively; N–O, Anomocora prolifera, INV CNI2725, off San Bernardo Islands, calicular view showing rejuvenescence stage and lateral view, both x 4.4; P–Q, Anomocora marchadi, INV CNI2303, off La Guajira, calicular and lateral views, both x 3.6; R, Coenosmilia arbuscula, INV CNI855, off San Bernardo Islands, branching pattern, x 1.5; S–T, Heterocyathus antoniae, paratype, INV CNI2076, off Manaure, calicular and lateral views, both x 4.5; U–W, Heterocyathus antoniae, INV CNI740, holotype, off Santa Marta (Neguanje Bay): U, basal view showing sipunculid holes, V, calicular view, and W, lateral view, all x 4.5. Scale bars for A–C, M, R = 1 cm; D–L, N–Q, S–W = 5 mm.