Pachycerianthus, Carter, 1995

Carter, Scott, 1995, Pachycerianthus (Anthozoa: Ceriantharia: Cerianthidae); two newly described species from Port Jackson, Australia, Records of the Australian Museum 47 (1), pp. 1-6 : 3-5

Pachycerianthus longistriatus n.sp.

Type material. HOLOTYPE: Taylors Bay, Port Jackson, silt over mussel debris, 5 m, coIl. P. Watts, 20 July 1989, AMG 15402. PARATYPES: Chowder Bay, Port Jackson, silt, 10 m, colI. S. Carter, 15 September 1989, AMG 15403; Port Jackson, Old Collection, c. 1886, 1 specimen, AMG 12553; Port Jackson, Old Collection, 3 specimens, G12554; Port Jackson, Old Collection, 1 specimen, AMG 12555; Dawes Point, Port Jackson, 5-6 fathoms, bucket dredge, colI. W.J. Hale, January 1933, AM G13558-G13561; Drummoyne, 3 August 1963, 2 specimens, AMG 15405; off Dawes Point, Port Jackson, 1933, colI. w.J. Hale, AMG 15406.

Description. Coloration of live animals. Column purple aborally merging to brown orally. Brown coloration may vary from dark to pale yellowish brown. Marginal tentacles all have a pale longitudinal stripe on each side with oral and aboral faces coloured, which gives them a distinctly striped appearance. Two tentacle colour forms: one pale yellowish brown the other deep purplish maroon. Labial tentacles pale cream. Oral disc deep brown in colour.

Coloration ofpreserved animals. Purple colour faded leaving column brown overall. Marginal tentacles, of the pale yellowish-brown colour form, fade to a pale cream, leaving stripes faintly visible. Maroon form retains faded purplish coloration. Labial tentacles almost white.

Length in preservative. 70-220 mm.

Tentacles. Arrangement of tentacles in pseudocycles: marginal tentacles, 2(dt)431.4231.4231...; labial tentacles, 3(dt)241.4231.4231... cycles 2 and 3 very difficult to separate. Directive labial tentacle present. Marginal tentacles number 138-140 (type 140), labial tentacles number 130-139 (type 138). Some marginal tentacles may be damaged at some time during animal's life and during regeneration a second tentacle may develop from a single tentacle base. When not actively feeding or in still water, distal third of marginal tentacles hang limply ( Fig. 1c ).

Siphonoglyph. Runs complete length of actinopharynx. Six attached mesenteries. Hyposulcus well developed, reaching one fifth length of siphonoglyph. Hemisulcus distinct but short.

Mesenteries. The directive mesenteries (B1) are short and may differ in length; m1 sterile, 1.5-3 x length of directives. Ciliated tract runs entire length of m1, craspedonemes may be present at distal end; b1 is 1- 1.5 x length of m1. Ciliated tract runs entire length of b1, craspedonemes may be present along distal half and cnidoglandular tract may be found at aboral tip of mesentery.

Mesenterial arrangement BmbM. All macromesenteries (M, m), except m1, are fertile, all micromesenteries (B, b) infertile. M1 long, reaching to aboral pole. M2 and M3 also long, almost reaching to aboral pole. Half to two-thirds of M1 occupied by ciliated tract and distal three-quarters carries craspedonemes. The m1 mesenteries less than half length of M1, ciliated tract confined to proximal three-quarters. Slight reduction in length of m mesenteries as they approach multiplication chamber. M mesenteries undergo substantial reduction in length after second quartette. Micromesenteries generally very short, B mesenteries twice length of b. All micromesenteries possess cnidoglandular tract. After first quartette, micromesenteries vary little in length ( Fig. 3 ).

Cnidom. Spirocysts, spirulae, atrichs and homotrichs are present. Cnida were examined and measured in two paratype specimens with ten capsules of each type measured from three samples (n = 60).

Atrichs are absent in the marginal tentacles and uncommon in the labial tentacles and homotrichs are confined to the column. Spirocysts were found in all organs except the column. Spirulae classes were generally restricted to two, with type 2 spirulae the most common in all tissues except the simple chord in the filaments.

Biology. This species occupies the same habitat as P delwynae , often living in close proximity. Similar commensal organisms are found associated with both species. One specimen has been kept on display at Taronga Aquarium for 21 years, during which time it has once produced offspring (1. West, pers. comm.), unfortunately the method of reproduction was not reported.

Remarks. Pachycerianthus longistriatus has M1 reaching the aboral pole, M2 and M3 almost reaching the aboral pole and m1 only being half the length of M1. A directive labial tentacle is present. M1 mesentery is short. These stable characters distinguish P longistriatus from other species of Pachycerianthus .

Etymology. The specific name longistriatus describes the longitudinal stripes on the marginal tentacles ( Fig. 1c ).

Figures

Fig. 1. a - Generalised view of organism; b - Pachycerianthus delwynae showing distinctive markings and coiled tentacles; c - Pachycerianthus longistriatus showing distinctive markings on the tentacles.

Fig. 3. Diagrammatic representation showing the right half of the internal arrangement of Pachycerianthus longistriatus, cut longitudinally and pinned flat. For explanation of key, see Figure 2.