Euthalenessa festiva (Grabe) Pettibone, M. H., 1970

Pettibone, M. H., 1970, Revision of the genus Euthalenessa Darboux (Polychaeta: Sigalionidae), Smithsonian Contribution to Zoology 52 : 12-18

Euthalenessa festiva (Grabe) , new combination

Figures 6-11

Leanira festiva Grube , 1875, p. 78; 1878, p. 56.

Thalenessa microeeras Haswell , 1883, p. 294.-Fauvel, 1917, p. 185.

Thalenessa oculata Mcintosh , 1885, p. 142, pi. 21: figs. 1,2; pi. 23: fig. 12, pi. 25: fig. 3, pi. 13A: figs. 11, 12.-Izuka, 1912, p. 86, pi. 10: figs. 1-2. [Not Sigalion oculatum Peters , 1854.]

Haswellia microeeras .-Darboux, 1900, p. 116.

Thalanessa [sic] oculata .-Moore, 1903, p. 426.-Benham, 1915, p. 201, pi. 45: figs. 118-123. [Not Peters, 1854.]

? Euthalenessa oculata .-Horst, 1917, p. 107, pi. 22: figs. 1-3. [Not Peters, 1854.]

Euthalenessa digitata .-Augener, 1927, p. 124.-Knox, 1960, p. 97, figs. 85-87 (part?). [Not Thalenessa digitata Mcintosh , 1885.]

Euthalenessa oculata .-Okuda, 1939, p. 226. Wesenberg-Lund, 1949, p. 258, fig. 3. [Not Peters, 1854.]

Thalenessa tropica Hartman , 1954, p. 228, fig. 1, a-d.- Gallardo, 1968, p. 53, pi. 6: figs. 7-12; pi. 7: figs. 1-5.

Thalenessa digitata .-Imajima and Hartman, 1964, p. 46. [Not Mcintosh, 1885.]

Material examined.- Pacific Ocean, exact locality unknown , Heller, collector - 1 specimen ( ZMB 3259 ) .

Port Molle , Queensland, Australia, 27.5 meters— of Thalenessa microceras Haswell ( AMS 11395 ) .

Off East Moncoeur Island, Bass Strait, 39° Vf S, 146° 37' E, 70 meters, sand and shells, Challenger Expedition, Station 162, 2 April 1874 '- holotype of Thalenessa oculata Mcintosh ( BMNH 1885: 12: 1: 110) .

Off Honshu Island , Japan, 57-75 meters, Albatross Station 3702 , 7 May 1900 -4 specimens ( USNM 5335 ) .

Sailus Ketjil , Paternoster Islands , 27 meters, coral and coral sand, Siboga Station 37 , 30/ 31 March 1899 - 1 specimen ( ZMA 312.1 ) . Haingsisi , Samau Island , Timor, shore exploration, Siboga Station 60 , 27/ 28 April 1899 -3 specimens ( ZMA 312.2) . Anchorage off North Ubian , 06° 07.5' N, 120° 26' E, 16-23 meters, Lithothamnion bottom, Siboga Station 99, 28-30 June 1899-1 specimen ( ZMA 312.3) . Anchorage off Pulu Tongkil , Sulu Archipelago , 13 meters, Lithothamnion bottom, Siboga Station , 109, 5/6 July 1899-3 specimens( ZMA 2035 ) . Anchorage off Sawan , Siau Island, 27 meters, stones and Lithothamnion , Siboga Station 125, 18/19 July 1899-1 specimen ( ZMA 2236 ) . 00° 7.2' N, 130° 25.5' E, 59-83 meters, grey muddy sand, shells, and Lithothamnion, Siboga Station 154, 14 August1899 -1 specimen ( ZMA 1779 ) . Banda anchorage, reef exploration, Siboga Station 240 , 22 November to 1 December 1899-8 specimens ( ZMA 312.4; RMNHL 1181 ; USNM 40575 ) . Anchorage off Rumah Lusi, Tiur Island, 54 meters, Siboga Station 248 , 4/5 December 1899-1 specimen ( ZMA 1900 ) . Anchorage east of Sailus Besar, Paternoster Islands, up to 36 meters, coral and Lithothamnion, Siboga Station 315, 17/18 February 1900-1 specimen ( ZMA 312.5) .

Ralum, Neu-Pommern , New Guinea, 66 meters, Fr. Dahl, collector - 1 specimen ( ZMB 6544 ) .

Onotoa , Gilbert Islands , August 1951, P. E. Cloud, collector - holotype and paratype Thalenessa tropica ( USNM 26088-89 ) .

Type-material.-The type of Leanira festiva Grube (1875) from the Philippine Islands no longer exists (Dr. G. Hartwich, in correspondence). The specimen described by Grube (1878) from the Pacific Ocean, exact locality unknown but probably below the equator, is deposited in the Berlin Museum ( ZMB 3259) and was used to supplement the description of the species (Figures 6, 7). It consists of anterior and middle fragments, with a total length of 69 mm, width of 6 mm, including setae, and 80 segments.

The holotype of Thalenessa microceras Haswell ( AMS 11395) consists of an anterior fragment of 65 segments, 40 mm in length, and 4 mm in width, including parapodia. Most of the blades of the neurosetae are broken off.

The holotype of Thalenessa oculata Mcintosh ( BMNH 1885: 12: 1: 110) consists of an anterior fragment and 2 middle fragments, with a total length of 54 mm, 6 mm in width, including setae, and 67 segments (Figure 11). The pharynx is partially extended and the palps are now missing.

The holotype of Thalenessa tropica ( USNM 26088) is 45 mm long, 3.5 mm wide, including setae, and 78 segments; the specimen is rather flabby and the pharynx is partially extended. The paratype ( USNM 26089) is a small specimen, 15 mm long, 2 mm wide, and has about 40 segments; all of the elytra are missing.

Description.-The body has a length up to 90 mm, width, including setae, 4-6 mm, with numerous segments-up to 180. The body is variously pigmented with rusty brown pigmentation, with prominent darker bands on setigers 14 to 16. The elytra may show mottled pigmentation in the form of brown areolae, with greater concentration on the anterior inner borders.

The elytra change in size and shape along the body. At first they are small and oval, then larger, subtriangular, subquadrangular, subreniform to subcordiform(Figures le-h; lOa-e; Ilk, I). The 1st pair of elytra lack papillae. The anterior elytra have fringes of papillae extending along most of their lateral borders, with 6 to 15 papillae; more posteriorly, the papillae are confined to the anterior halves of the lateral elytral borders, with 13 to 10 papillae. Most of the papillae are irregularly palmately or dichotomously branched, with 2 to 9 filaments per papilla.

The pharynx was not fully extended on any of the specimens examined.

The fused prostomium and tentacular segment are wididrawn widiin die anterior few setigers (Figures 6a, b; 8a; 11a). The 2 pairs of eyes are large, closely approximated, located on more or less inflated, raised ocular areas, die anterior pair being larger dian die posterior pair; the posterior two-thirds of die prostomium is covered dorsally by setigers 2-4. The ceratophore of the median antenna extends from a wider median area between the anterior pair of eyes, narrowing slighdy more distally where it is fused to die dorsal sides of the fused tentacular parapodia. The ceratophores of die lateral antennae, which are also fused to die dorsal sides of die tentacular parapodia, extend beyond die median ceratophore; die 3 free antennal styles are subequal in size, short, and subulate. The long palps extend posteriorly to about setigers 17-18. The dorsal tentacular cirri are short and tapered; die ventrai tentacular cirri are about twice as long as the dorsal (Figure 8b). The inner dorsal tentacular ridges are found on the distal third of the tentacular lobes, with 2 groups of capillary setae emerging laterally from near both ends of the ridges; the setae are few in number or may be absent The bulbous facial tubercle is visible ventrally between the lateral lips and the inner palpal sheaths; a pair of small labial ctenidia are found on the lateral lips (Figures 6fc; 11a).

The parapodia of setigers 2-5 are gready modified, with well-developed bracts (Figures 6a-e; Sa, c-g; lib). The anterior and posterior notopodial bracts encircle the compact bundles of notosetae; the bracts are variously slashed with 2-3 anterior and 1-4 posterior stylodes. The neuropodial bracts are as follows: (1) lower-anterior-ventral bracts, greatly enlarged and flaring; they are longest on setigers 2 and 3, becoming shorter on setigers 4 and 5; (2) upper-anterior bracts, shorter and wider; their lower distal parts form more or less distinct rounded lobes or ligules, which are directed inward; (3) lower-posterior bracts, subconical and directed upward; and (4) upper-posterior bracts formed of digitiform stylodes 6-9 in number. In the following transitional setigers, the lower-anterior and upper-anterior bracts become shorter and rounded, with a notch between (Figure 9a). The lower-posterior bracts become shorter and oval; upper-posterior stylodes are fewer in number, the lower one becoming greatly enlarged and surpassing in size the lower-posterior bract (Figure lie). By setigers 7-8, the stylodes have disappeared and the posterior bract is continuous, although there may be a distal notch (Figure 96). The long slender compound neurosetae of the anterior setigers have multiarticulate blades with 4-8 articles; some of the neurosetae are stouter, their blades shorter with 2 articles; the stems are smooth or have few spinuous rows (Figures 6d; 8d, f). The dorsal cirri on setiger 3 are short, subulate, borne on short cirrophores (Figures 6a, e; 8a, e). Small ctenidia encircle the elytriphores of setiger 2 and the dorsal cirri of setiger 3 (Figures 6a, c, e; 8a, c, e).

The branchiae begin on setigers 4-7. The parapodial ctenidia are large, cup-shaped, 3 per parapodium. The parapodia of the anterior segments have small clubshaped notopodia and larger neuropodia (Figures 7a-c; 9d-f; lle-g). The notopodial bracts have a single posterior and 1-2 anterior stylodes. The notosetae form rather small bundles; they are slender, spinous, tapering to capillary tips. The neuropodial acicular lobes are enclosed in anterior and posterior bracts. The G-shaped posterior bracts are diagonally truncate and enclose the C-shaped rows of neurosetae. The smaller lower-anterior bracts are truncate and enclose the lower diagonal rows of neurosetae. The larger upper-anterior bracts are rounded, with distinct rounded lobes or ligules on their lower borders; the ligules are directed inward below die tips of the acicular lobes; the upper borders of the bracts curve around the upper diagonal rows of neurosetae. The compound neurosetae are moderately stout; the distal tips of the enlarged stems have few faint to distinct spinous rows; the blades are short to moderately long, the lower ones being 2-3 articled (Figures 7c; 9/; lia). The ventral cirri are slender, tapering, extending to the distal tips of the neuropodia or slightly beyond.

The parapodia of die middle and posterior regions of the body are somewhat modified (Figures 9g, h; llh-j). The notopodia are similar, having 0-1 posterior and 1-2 anterior stylodes. The neuropodia show more marked changes. The posterior bracts are more elongate and subconical. The upper-anterior bracts are smaller and more or less fused with the acicular lobes in the areas where die neurosetae are lacking; this includes their lower ligules, which are directed downward below the tips of the acicular lobes. The neurosetate are longer; their stems may have more numerous, distinct spinous rows; the blades are somewhat longer, those of the upper neurosetae have 2-3 articles and the lower more slender ones have 3-5 articles (Figures Id; 11;'). The ventral cirri are longer and extend beyond the distal tips of the neuropodia.

Distribution.-Indo-Pacific: Gulf of Iran, Japan, Philippine Islands, Malay Archipelago, New Guinea, Australia, New Zealand, Marshall Islands. Intertidal to 83 meters.

Remarks.-Knox (1960) combined the 3 Thalenessa species of Mcintosh (1885) - T. oculata , T. digitata and T. fimbriata - under Euthalenessa digitata Mcintosh ). Based on reexamination of the type-specimens, die 3 species are herein considered to be distinct and T. oculata Mcintosh is referred to E. festiva (Grube) . Part of Knox's records of Euthalenessa digitata from the Chamam Island questionably may refer to E. festiva .

The record of Monro (1924) of E. oculata (Mcintosh) from Torres Strait and China Sea is questioned. Nine specimens, deposited in the British Museum ( BMNH 1925: 1: 28: 50), were examined. They appear to be a different species but, due to the poor condition of the specimens, they were not studied in detail.

Examination of tìie holotype of Thalenessa microceras allows some corrections of the original description to be made. The elytra are located on segments 2, 4, 5, 7, and alternate segments to 27, then continuing on every segment (not on every second segment, as stated by Haswell). A pair of short dorsal cirri is found on segment 3; branchiae begin on segment 6; dorsal tubercules are found on segments 6, 8, and alternate segments to 26 (branchiae on dorsal tubercles referred to as dorsal cirri by Haswell; branchiae on elytriphores referred to as cirriform appendages). The long palps extend to segments 14 and 17 (called buccal tentacles by Haswell). Except for the first few segments, the parapodia were not described by Haswell; they agree with the description given above.