Anozopathes hawaiiensis, Opresko & Bo & Stein & Evankow & Distel & Brugler, 2021

Opresko, Dennis M., Bo, Marzia, Stein, David P., Evankow, Ann, Distel, Daniel L. & Brugler, Mercer R., 2021, Description of two new genera and two new species of antipatharian corals in the family Aphanipathidae (Cnidaria: Anthozoa: Antipatharia), Zootaxa 4966 (2), pp. 161-174 : 164-167

Anozopathes hawaiiensis sp. nov. Opresko & Bo

( Figs 2–3 )

Material examined. Holotype: USNM 1010741 ( NMNH SEM stub 171), Hawaii, Penguin Bank, Molakai , 21.974ºN, 157.369ºW, DSR/ V Pisces IV, Dive 066 (spec. 4), 298 m, Hawaii Undersea Research Laboratory, coll. E. Chave, 27 Oct 2002 . Paratype: USNM 99927 , Hawaii, French Frigate Shoals , 23.9175ºN, 165.368ºW , R / V Townsend Cromwell , SANGO Exped. XIII, 353–381 m, coll . R. Grigg , 21 Aug 1972 .

Type locality. Hawaii, Penguin Bank , 298 m.

Diagnosis. Colonies small, very sparsely branched to the second order but possibly up to the fourth order based on in situ photos; with long, curved and crooked branches disposed irregularly on all sides of the stem. Branch angles usually close to 90º. Polypar spines up to 0.25 mm tall, 0.7–0.9 mm apart, with 2–3 spines per mm in each row. Polypar spines with up to six small conical tubercles visible near the apex in lateral view. Polyps up to 3.6 mm in transverse diameter, arranged in a single series, with three to five polyps per cm.

Description of holotype. The holotype (USNM 1010741) is about 24 cm tall and 15 cm wide, and has a basal stem diameter of about 2 mm ( Fig. 2A ). The main stem is 41 cm long and curved and coiled at its upper end. The branching is very sparse, and only to the second order. The branches are long, flexible and curved to varying degrees. The longest branch measures about 18 cm and is 1 mm in diameter at the base. The branches are spaced varying distances apart, with distal branch angles mostly around 90º.

The spines ( Fig. 2C–D ) appear conical in side view, but are distinctly compressed laterally. Most are slightly inclined distally. The shape of the spines is not uniform; in some the proximal and distal edges are relatively straight whereas in others the proximal edge near the base is flared out in a shallow slope. On a section of a branch 0.3 mm in diameter the polypar spines reach a maximum size of about 0.24 mm (as measured from middle of base to apex) and the abpolypar spines are about 0.13 mm. On a section of a branch 0.4 mm in diameter the polypar spines reach a maximum size of about 0.25 mm and the abpolypar spines are about 0.15 mm. Most of the polypar spines have a few conical tubercles near the apex; the apex itself is generally smooth and rounded. The abpolypar spines are less likely to have tubercles, but even some polypar spines are lacking tubercles. The conical tubercles are up to 0.005 mm tall; and up to six can be seen in one lateral view; however, on many spines fewer than six are visible in lateral view. The spines nearer the distal end of the branches have very few if any tubercles. Four to six longitudinal rows of spines can be seen in one lateral view (excluding rows in which the spines are only partially visible). Within each row the spines are mostly 0.7–0.9 mm apart, resulting in about two spines per mm. On the stem the spines are about 0.14 mm tall and similar in shape to those on the branches. In some places the bases of the spines in one row are joined together into a continuous ridge-like structure.

The polyps are arranged in a single row ( Fig. 2B ). In the preserved state most measure about 3 mm in transverse diameter (from the distal side of the base of the distal lateral tentacles to the proximal side of the base of the proximal lateral tentacles), but in a few places some reach a size of about 3.6 mm. The interpolypar space is close to 0.5 mm, and there are about three polyps per cm. The tentacles in the preserved state are 2 mm in length, and there is no apparent difference in the size of the sagittal and lateral tentacles.

Species variation. The paratype (USNM 99927) is similar to the holotype in general appearance with a few long, thick branches. The polypar spines are up to 0.22 mm tall, but most are 0.18 mm or less. On the 1.5 mm thick stem the spines are about 0.16 mm tall. In this specimen the polyps, 2 to 2.5 mm in transverse diameter, are smaller than those in the holotype, and the polyp density is correspondingly greater (about five polyps per cm).

Comparisons. One other species is assigned to the genus, Anozopathes palauensis sp. nov. (see description below). The two species have a similar growth form, with sparse branching and wide distal branch angles; however, the branches in A. hawaiiensis sp. nov. tend to be rather crooked and orientated in different directions whereas those in A. palauensis sp. nov. are mostly curved upward. The major difference between the two species is in the size and shape of the spines ( Table 2 ). The polypar spines in A. hawaiiensis are up to 0.25 mm and relatively narrow, whereas those in A. palauensis are shorter, up to 0.14 mm, and have a relatively wide base with a very shallow sloping proximal edge. Although the number of rows of spines is similar in the two species, the spines in A. hawaiiensis appear to be slightly more distant and have slightly fewer tubercles (up to about 6 vs. up to 8, as seen in lateral view). The size and density of the polyps in the two species overlap; however, the polyps in A. hawaiiensis reach a greater maximum size (3.6 mm in transverse diameter).

Anozopathes hawaiiensis sp. nov. is similar in external appearance to small colonies of Antipathes dichotoma Pallas, 1766 ; the polyps are of similar size, and the general morphology of the spines is similar ( Opresko, 2003; Bo et al. 2011). The one major difference is that the spines of A. hawaiiensis sp. nov. have tubercles; whereas tubercles have never been found on the spines of A. dichotoma . However, in separate genetic studies using the mt gene region cox3-cox1 ( Brugler et al. 2013) and nuclear ITS1/ITS2 ( Bo et al. 2018), specimens of A. dichotoma showed affinities to several species in the family Aphanipathidae , suggesting that tubercles may have been secondarily lost in this species. If the relationship of A. dichotoma to the Aphanipathidae is confirmed by more extensive genetic studies, such as those using ultra conserved elements and exon loci ( Quattrini et al. 2017, 2020; Horowitz et al. 2020; Mc- Fadden et al., 2021), a taxonomic revision of the families Antipathidae and Aphanipathidae will be necessary.

Etymology. The species name is based on the type locality.

Distribution. Known only from Hawaii; 298– 381 m. Observations made from ROVs ( Fig. 3 ) suggest that the species might be fairly abundant in certain areas around the Hawaiian Islands. Although the growth form of the species is quite distinctive, we cannot confirm that the colonies shown in Figure 3 are A. hawaiiensis sp. nov.

Figures

FIGURE 2. Anozopathes hawaiiensis sp. nov. holotype (USNM 1010741): A. entire corallum; B. polyps; C. individual polypar spines with tubercles; D. sections of branchlets (C and D from NMNH SEM stub 171).

FIGURE 3. In situ image of colonies presumed to be Anozopathes hawaiiensis sp. nov. Photo: J. Maragos, 1982, Puna, Hawaii, 349 m.