Acryptolaria patagonica El Beshbeeshy, 1991

Watson, Jeanette W., 2003, Deep-water hydroids (Hydrozoa: Leptolida) from Macquarie Island, Memoirs of Museum Victoria 60 (2), pp. 151-180 : 162-163

Acryptolaria patagonica El Beshbeeshy

Figures 12A–C

Acryptolaria patagonica El Beshbeeshy, 1991: 67 , fig. 14.

Material examined. Stn 90, TM K2777, stem 50 mm high, NMV F91318 stem fragments 5 mm high, all detached from substrate, specimens alcohol-preserved. Stn 90, NMV F91337, malinol-mounted microslide from stem fragment. Stn 94, NMV F91319, colony 100 mm high, two stems 50 mm high joined at base but detached from substrate, three stems to 5 mm high and stem fragment; on primnoid gorgonian, specimens alcohol-preserved. Stn 130, TM K2778, stem 50 mm high, detached from substrate, specimen alcohol-preserved.

Description. All colonies infertile. Stolons reptant on substrate, tubular, narrow, coalescing into erect, almost straight stems; sometimes single hydrothecae arising from stolons between stems. Taller stems to 2 mm thick at base, basal 5–10 mm unbranched; lower stem region strongly fascicled, polysiphonic tubes mostly linear, running up stem and along primary branches. Complex colonies with up to four orders of branching; branches more or less alternate, usually in one plane, primary and subsequent branches often originating just above a hydrotheca, ultimate branches (hydrocladia) and some branches in lower stem region monosiphonic.

Hydrothecae biseriate, tubular, subalternate, usually frontal on branch, long, gracefully arched outwards, abcauline wall concave, often a minor swelling in proximal wall; adcauline wall smoothly convex, one third adnate to hydrocladium, adnate part narrowing a little proximally and fading into hydrocladium; hydrocladium fairly narrow behind adnate hydrothecal wall. Margin circular, transverse to hydrothecal axis, rim slightly everted, almost parallel to hydrocladial axis; margin may have up to 14 close replications bending plane of rim away from axis of hydrotheca. Cauline hydrothecae partially immersed in polysiphonic tubes of stem and primary branches; tubes then often contorted around hydrothecae.

Hydranths contracted and wrinkled; with c. 20 tentacles and clavate hypostome; hydranth attached to base of adnate hydrothecal wall by a ring of tissue.

Perisarc of stem and branches thick and smooth, perisarc of hydrothecae thinner and shining.

Colour. Stems pale honey-yellow fading to almost colourless at tips of branches. Hydranths may have been deep goldenbrown.

Measurements (µm)

Branch distance between hydrothecae on monosiphonic branch 900–1200

width of hydrocladium where adnate hydrothecal wall becomes free 104–136 Hydrotheca length (diagonal) of free adcauline wall including marginal replications 1500–1600

length of adnate adcauline wall from base of hydranth 880–1040

width at base of hydranth 232–256

diameter at margin 416–448

Distribution. Patagonian shelf ( El Beshbeeshy, 1991). Also recorded from 415–1060 m at 39˚–55˚S, near Macquarie Island ( Vervoort and Watson, 2003).

Remarks. The larger colonies are rather flexuous and the ultimate monosiphonic branches are quite lax out of fluid. The long, curved hydrothecae are characteristic. The free part of the hydrotheca is tubular but the adnate adcauline hydrothecal wall narrows, becoming increasingly indefinite and rather fibrous in appearance as it passes downward into the hydrocladium.

The frontally directed, long curvaceous hydrothecae resemble Acryptolaria patagonica more than any other known species of the genus. Although the habit of the present specimens differs somewhat from descriptions of A. patagonica , this may be due to immaturity of the colonies. It is unfortunate that the present material is infertile, since a coppinia would confirm its identity.

Figures

Figures 12A–C. Acryptolaria patagonica, stn 44. A, colony. B, hydrothecae. C, multiple replications of hydrothecal margin. Scale bar: A, 12 mm; B, C, 1 mm.