Anthoptilum lithophilum, Williams, Gary C. & Alderslade, Philip, 2011

Williams, Gary C. & Alderslade, Philip, 2011, Three new species of pennatulacean octocorals with the ability to attach to rocky substrata (Cnidaria: Anthozoa: Pennatulacea), Zootaxa 3001, pp. 33-48 : 36-38

Anthoptilum lithophilum sp. nov.

Figs. 2–3 , 6 C, 8D, 10

Material examined. HOLOTYPE: CAS 179453, sample number T666-R10, California, Northeast Bank, Outer California Borderlands, 32.2716305° N, 119.6724745° W, 669 m depth, 3 May 2004, MBARI, on basaltic lava.

PARATYPE: CAS 179454, sample number T628-A4, California, Rodriguez Seamount, 34.057368° N, 121.052983° W, 700 m depth, 14 October 2003, MBARI, on volcaniclastic pavement. OTHER: CAS 179456, Anthoptilum sp. indet., Hawai’i, Niihau, 21° 59.250’N, 160° 12.631’ W, Site: NW-1c, 368 m depth, 3 May 2010, HURL, one damaged specimen.

Diagnosis. Ratio of total colony length to rachis diameter approximately 50:1. Autozooids 10–15 mm long, 2– 4 mm wide. Adjacent autozooids closely placed in indistinct, slightly oblique rows. Autozooid walls with minute oval sclerites, each usually less than 0.01 mm in length. Proximal terminus of peduncle modified into a markedly widened structure with a protruding, conical, terminal knob covering the end of the axis.

Description. The holotype ( Fig. 2 A) is 118 mm long with the polyp-bearing rachis occupying 98 mm (or 83%) of the entire length. Approximately 45 autozooids are arranged along the length of the rachis, which are 9–16 mm long and not readily discernible as biserial, opposite, sub-opposite or alternate, being more randomly placed. In one 10 mm long autozooid, the polyp wall is 7 mm long, while tentacle length is 3 mm. Siphonozooids are conspicuous, approximately 0.3–0.4 mm in diameter, and appear as white hemispherical protuberances arranged in several longitudinal rows on both sides of each longitudinal row of autozooids. Sclerites are scattered, minute oval bodies, less than or equal to 0.01 mm long, present only in the body walls of the autozooids ( Fig. 3). The rachis of the preserved specimen is grayish-white and the autozooids are tan.

Variability. The paratype is 95 mm long with a mauve rachis/peduncle and dark purplish-brown autozooids.

Etymology. The specific epithet lithophilum is derived from the Greek (lithos —stone) and (philos —loving, fond of, having affinity for), alluding to this species inhabiting rocky substrata.

Distribution. Presently known only from off the coast of California, U.S.A.; 669–700 m in depth ( Fig. 10 ).

Differential diagnosis. Anthoptilum lithophilum sp. nov. has sclerites in the polyp walls but these are lacking in all other species of the genus. The ratio of colony length to rachis diameter is 50:1, but the ratio in the other species is as follows: A. grandiflorum , up to 100:1; A. murrayi ( Kölliker, 1880) , 93:1; A. decipiens sp. nov., 180:1; A. gowlettholmesae sp. nov., up to 30:1.

Remarks. One damaged, additional specimen collected from Niihau, Hawai’i (CAS 179456), is considerably laterally compressed and significantly flattened. Although it does show a superficial resemblance to Anthoptilum lithophilum sp. nov., its identification remains uncertain.

Figures

FIGURE 2. Anthoptilum lithophilum sp. nov.: A, holotype CAS 179453; B, paratype CAS 179454.

FIGURE 6. Rock-inhabiting sea pens, in situ, scales not given: A – B, indeterminate taxon, Hawai’i, note the axis in the translucent sucker in image B (images courtesy of HURL); C, Anthoptilum lithophilum sp. nov., central California (photo courtesy of MBARI); D, indeterminate taxon, New Zealand (photo courtesy of NIWA). [Colonies in A, B, C only photographed and assumed to be on hard substrate]

FIGURE 10. World map showing known geographic locations of rock-inhabiting sea pens: = Anthoptilum gowlettholmesae sp. nov.; = Anthoptilum lithophilum sp. nov.; = Calibelemnon francei sp. nov.; + = Anthoptilum decipiens; * = taxa indeterminate; from specimen CAS 179456 (Hawai’i) and / or underwater images (Hawai’i and New Zealand).