Euchelipluma elongata, Lehnert, Helmut, Stone, Robert & Heimler, Wolfgang, 2006

Lehnert, Helmut, Stone, Robert & Heimler, Wolfgang, 2006, New species of deep­sea demosponges (Porifera) from the Aleutian Islands (Alaska, USA), Zootaxa 1250, pp. 1-35 : 17-20

Euchelipluma elongata sp. nov.

( Fig. 10 a–b, Fig. 11 a–f)

Description

Yellowish colored whip­like sponge ( Fig. 10 a–b), resembling species of Asbestopluma Topsent, 1901 and Esperiopsis flagrum sp. nov. (see below) Rigid long, thin stalk with thin, relatively short processes. The collected specimen is broken at the tip, but still 32 cm in length, attached to the substrate by a rigid root system. May attach to exposed bedrock, boulder, cobble, and pebbles partially buried in unconsolidated sediment. The axis is flattened, measuring 2 x 3.5 mm, with two rows of filament­like processes (0.1 x 7 mm) on the narrow sides of the axis.

Skeleton: The ectosome consists of densely arranged isochelae, underlaid by paralleloriented fusiform styles with blunt ends and smaller tylostyles. Single tylostyles are placed perpendicular to the orientation of the styles and tylostyles.The choanosome is dominated by ascending polyspicular tracts of styles, tylostyles and isochelae. In the central axis of the stalk individual tracts are no longer recognizable but it consists almost exclusively of extremely densely packed, parallel arranged styles with occasional tylostyles perpendicular to the styles and many microscleres in between.

Spicules: Megascleres are blunt ended, fusiform styles ( Fig. 11 a), 1310–1510 x 40 –55 µm, tylostyles ( Fig. 11 c), often with the tyle subterminal, occasionally polytylote ( Fig. 11 e), 620–660 x 9–13 µm. Microscleres are isochelae ( Fig. 11 b), 80–95 µm, placochelae ( Figs. 11 d, e) 70–88 µm and sigmas ( Fig. 11 f), 9–25 µm.

Discussion

The present species fits well into the diagnosis of Euchelipluma according to Hajdu & Lerner (2002:653), of “ Guitarridae with narrow placochelas in face view, smooth palmate isochelae, sigmancistras and an erect habit coupled to axially compressed architecture”.There are only three other known species of the genus: E. pristina Topsent, 1909 , E. arbuscula Topsent, 1928 and E. congeri de Laubenfels, 1936. E. pristina is described from the Cape Verde Islands (Atlantic) from 91m depth. It is a small species, only 14–22 mm in height, but also of whip­like growth form. Its styles are only slightly fusiform and shorter (up to 1000 x 30 µm) as are the subtylostyles (370–600 x 14–24 µm). The palmate isochelae (80–100 µm) are of the same size while the placochelae of E. pristina (60–73 µm) are smaller than those of E. elongata . E. pristina has two size categories of sigmancistras (large, 22–24 µm, and small, 12 µm) versus only one cateogory in E. elongata . E. arbuscula (Topsent, 1928) known from Japan is a branched sponge with a maximum height of 4.9 cm and thus clearly differs in growth form and size. It is clearly different from the present species in having desmas (lacking in our species), smaller styles (413–455 x 15–17 µm) and additional polytylote strongyles (85–140 x 5–12 µm), again lacking in E. elongata . The (sub­)tylostyles (up to 180 x 2–5 µm) of E. arbuscula are much smaller. Its palmate isochelae (24–28 µm) are about 25% of the length of those in E. elongata , and the placochelas (52–58 µm) are much smaller than those in E.elongata . E. arbuscula has two size categories of sigmas (large, 50–65 µm, and small, 25–43 µm) while the sigmas of E. elongata are much smaller size. E. congeri (de Laubenfels, 1936) is known from the Caribbean Sea at a depth of 1047 m. It is a small (13 mm height, 9 mm in diameter) conical sponge with a fistulose upper surface. It lacks the large category of styles, the tylostyles (553– 1004 x 9–13 µm) occur in a much broader range of sizes and exceed the size of the tylostyles of E. elongata . Palmate isochelae are probably lacking; de Laubenfels could not confirm this. The placochelae (13–15 µm) are considerably smaller while the sigmancistras are about the same size. E. congeri differs in growth form, in lacking large styles and palmate isochelae, and in the dimensions of the tylostyles and the placochelae.

Though E. arbuscula is geographically the closest record of another Euchelipluma , E. pristina from the Atlantic seems to be the most similar congener, although differing considerably in size and dimensions of the spicules. E. elongata is the longest Euchelipluma recorded and exceeds by far the size of E. arbuscula which is the second largest with a height of only 4.9 cm.

Distribution

Known only from the type locality. This is the first record of the genus from the Aleutian Islands. This species may be common in the central Aleutian Islands. Sponges similar in gross morphological appearance to E. arbuscula (e.g. Esperiopsis flagrum n.sp.) are common in many areas of the study region but are difficult to differentiate from one another without collection.

Etymology

Referring to the length of the species.

Figures

FIGURE 10. Euchelipluma elongata sp. nov. a, holotype in situ at 2162 m depth south of Amlia Island. b, holotype after collection.

FIGURE 11. Euchelipluma elongata sp. nov. a, Fusiform choanosomal style. b, isochela and sigmas. c, Ectosomal tylostyle, slightly polytylote. d, Characteristic thin placochela. e, Developmental stage of polytylote tylostyle and two placochelae. f, Sigma.