Holothuria (Mertensiothuria) fuscorubra Théel, 1886

Yves, 2003, The holothurian subgenus Mertensiothuria (Aspidochirotida: Holothuriidae) revisited, Journal of Natural History 37, pp. 2487-2519 : 2497-2499

Holothuria (Mertensiothuria) fuscorubra Théel, 1886

(figures 4A–L, 11B, 12E)

Holothuria fusco-rubra Théel, 1886: 182 , pl. 7, figure 2; Sluiter, 1901: 15; H. L. Clark, 1902: 527; Fisher, 1907: 661, pl. 68, figures 3, 3a–e; Pearson, 1913: 77, pl. 11, figure 16a–d; Schmidt, 1925: 134; Cherbonnier, 1951: 32, pl. XI, figures 11–18, pl. XIII, figures 1–12, 14; Deichmann, 1958: 298 (cited as a synonym of H. (M.) leucospilota ); Rowe, 1969: 164 (cited as a synonym of H. (M.) leucospilota ).

Holothuria fuscorubra: H. L. Clark, 1925: 103 .

Holothuria (Holothuria) curiosa var. fusco-rubra: Panning, 1931: 208 , 209, figure 1b; Panning, 1933: 132, figures 7–10; Panning, 1935d: 5, figure 108; Panning, 1935e: 18, 26, figure 19.

Holothuria (Mertensiothuria) fusco -rubra: Marsh et al., 1993: 64.

Holothuria (Mertensiothuria) fuscorubra: Rowe and Gates, 1995: 293 ; Rowe and Richmond, 1997: 304; Samyn et al., 2001: 104, 107.

Holothuria isuga Mitsukuri, 1912: 87 , text figure 18.

Holothuria pardalis?: Heding, 1940: 123 , figure 6.

Original name. Holothuria fusco-rubra Théel, 1886 .

Name-bearing type. Holotype, NHM 1886.10.2.173.

Type locality. Hawaiian Is. (as Sandwich Isles).

Current status. Holothuria (Mertensiothuria) fuscorubra Théel, 1886 .

Material examined. Tuvalu (Ellice Islands, north and south ends Nukufetau), 1952, unknown depth, coll. Challenger, NHM 1952.5.7.1 (one specimen) .

Description. Medium-sized, voluminous species with length of live specimens up to 400 mm (Rowe and Richmond, 1997). Ventral and dorsal body colour in alcohol uniform chestnut brown (figure 12E). Body wall with many transversal folds after preservation. Ventral and dorsal tube feet sparsely distributed, more densely crowded in the ambulacral areas than in the interambulacral ones. Mouth ventral, surrounded by 20 (Fisher, 1907; Cherbonnier, 1951) green to chestnut brown tentacles. Anus terminal surrounded by a single ring of papillae. Very well-developed bifid longitudinal muscles. Cuvierian tubules present according to Cherbonnier (1951), but not reported from the examined specimen.

Ossicles: in the ventral and dorsal body wall (figure 4A–D) tables and buttons. Tables of the ventral body wall (figure 4A) numerous, disc 40–60 m m across, perforated by four central holes and 4–10 peripheral holes of various sizes; disc quadrangular or more rounded with a spiny rim; pillars short (single cross-beam) ending in a spiny crown with a large central opening; often crown incomplete. Tables of the dorsal body wall (figure 4C) similar in shape but with discs of 53–70 m m across. Buttons of ventral and dorsal body wall (figure 4B, D) numerous, 40–60 m m long, with three pairs of regular holes; rim of button always smooth, slightly irregular. Ventral tube feet with plates, buttons and tables (figure 4E–G); plates (figure 4E) up to 110 m m long and 75 m m wide, with up to four rows of holes of different sizes; buttons (figure 4F) numerous, up to 75 m m long, with three to four (occasionally five) pairs of holes, rim of button smooth, but highly irregular; tables similar in shape as the ones in the body wall, however, crown more often only partially formed. Dorsal tube feet with plates, buttons and tables (figure 4H–K); plates (figure 4K) up to 110 m m long and 75 m m wide, up to four rows of holes of different sizes; tables and buttons (figure 4H, J) similar to the ones in the ventral tube feet. Anal papillae (figure 4K) with rods, 40–155 m m long, sometimes perforated by one or several holes. Longitudinal muscles (figure 11B) with rings and rods from 25 to 42 m m long, rods often perforated by one or two holes.

Diagnosis. Present note.

Ecology. Not specified in the original description. The gut of NHM 1952.5.7.1 contains coarse sand. According to Rowe (in Rowe and Gates, 1995) it has a benthic, inshore, detritus- and deposit-feeding habit. Rowe (personal communication) notes that H. (M.) fuscorubra tends to live in exposed locations and that a mucus coating often envelops the animal.

Geographical distribution. Tropical Indo-west Pacific (Rowe and Gates, 1995).

Proposed status. Holothuria (Mertensiothuria) fuscorubra Théel, 1886 .

Comments. Although Cherbonnier (1951) noted small rods with lengths of about 50 m m in the tentacles, these were not observed by us in the material examined. We agree with Rowe (in Rowe and Gates, 1995) in raising H. (M.) fuscorubra from synonymy of H. (M.) leucospilota since comparison of the ossicle assemblage of individuals of similar body length (77 mm length for H. (M.) fuscorubra versus 80 mm length for H. (M.) leucospilota ) reveals several differences: (1) the disc of the tables found in the body wall of H. (M.) leucospilota is round to slightly quadrangular and moderatly spinose (figure 6B, G) while for H. (M.) fuscorubra it tends to be more quadrangular and more spinose (figure 4A, C); (2) the spire of the tables found in the body wall of H. (M.) leucospilota (figure 6B, G) generally is better developed, with one or two cross-beams, than that of H. (M.) fuscorubra , with one or no crossbeam (figure 4A, C); (3) the crown of the tables found in the body wall is generally narrow, but rather well developed in H. (M.) leucospilota , while for H. (M.) fuscorubra it is often reduced (as already observed by Théel, 1886; Sluiter, 1901; Pearson, 1913; Cherbonnier, 1951), or when present wide; (4) the number of peripheral holes in the table discs of H. (M.) leucospilota is greater (figure 6B, G) than that present in H. (M.) fuscorubra ; (5) the buttons of H. (M.) leucospilota have three to four pairs of irregular holes and an irregular rim (figure 6D, H), while those of H. (M.) fuscorubra have two to three pairs of holes and have a more regular outline (figure 4B, D); (6) the plates in the ventral tube feet of H. (M.) leucospilota are elongated to oval, perforated by numerous small holes (figure 6L), while in H. (M.) fuscorubra they are wider with large perforations (figure 4E); (7) the dorsal tube feet of H. (M.) leucospilota have no plates per se but variously perforated rods (figure 6T), while those of H. (M.) fuscorubra show well-developed plates of various sizes (figure 4K) and no rods. In addition, Rowe (personal communication) observed that H. (M.) fuscorubra lives in more exposed locations whereas H. (M.) leucospilota is almost invariably found in semi-cryptic locations (see also figure 12G), and that H. (M.) fuscorubra tends to develop a mucus envelope around its body. It is, however, noteworthy that Rowe (personal communication) is uncertain whether these observations are associated with growth and changes in ecology with age, or whether they are true characteristics of the species.