Acryptolaria pygmaea, Peña Cantero & Vervoort, 2010

Peña Cantero, Álvaro L. & Vervoort, Willem, 2010, Species of Acryptolaria Norman, 1875 (Cnidaria, Hydrozoa, Lafoeidae) collected in the Western Pacific by various French expeditions, with the description of nineteen new species, Zoosystema 32 (2), pp. 267-332 : 320-321

Acryptolaria pygmaea n. sp.

( Figs 27 ; 30 ; 32J ; Table 28)

MATERIAL EXAMINED. — Norfolk Ridge. SMIB 4, stn DW 60, 23°00.1’- 22°59.4’S, 167°21.6’- 167°21.7’E, 500-535 m, 10.III.1989, 1 stem c. 11 mm high, holotype (MNHN-Hy.2009-0173).

Coppiniae without defensive tubes. Gonothecae flask-shaped, tightly set together and with coalesced walls ( Fig. 26D, E ). Diameter strongly decreasing distally, forming a short neck ( Fig. 26E ) with a circular aperture ( Fig. 26D, E ).

ETYMOLOGY. — The specific name pygmaea , latinization of the Greek adjective “pygmeios”, small, refers to the dwarf hydrothecae; it follows in gender the (feminine) genus name.

ECOLOGY AND DISTRIBUTION. — Acryptolaria pygmaea n. sp. was collected at depths between 500 and 535 m in the Norfolk Ridge area.

DESCRIPTION

Stem 11 mm high, in bad condition and with extremely fragile perisarc.The stem has only two primary branches, each with a secondary branch ( Fig. 32J ).

Hydrothecae alternately arranged in approximately one plane ( Fig. 27A ), tubular, practically cylindrincal ( Fig. 27 ); diameter decreasing only in the extreme basal part. Hydrotheca smoothly curved outwards, adcauline wall convex,adnate over a variable extension, from about one-half to five-sixths of its lengh (adnate/ free ratio 1.3-5.3); abcauline wall concave, though straight or slightly convex in its basal part.Hydrothecal aperture circular and directed outwards, virtually parallel to long axis of branches; rim even.

Large nematocysts relatively very large and fusiform ( Fig. 30 ).

Coppinia not observed.

REMARKS

Notwithstanding the scarcity of material, we consider that Acryptolaria pygmaea n. sp. is an easily identifiable species. It is well characterized by its relatively tiny hydrothecae and huge nematocysts. It is allied to A.minuta and A.minima in the size of the hydrothecae, being closer to the former by the relatively long and thin hydrothecae.However, it is easily distinguishable from these two species by the size of the nematocysts that are distinctly larger than those of A.minima (25.8 × 9.8 µm in the holotype) and much larger than those of A. minuta (16.7 × 6.3 µm in the holotype).

Figures

FIG. 27. — Acryptolaria pygmaea n. sp., from SMIB 4 stn DW 60, branch fragments showing hydrothecal arrangement and hydrothecae. Scale bar: 250 μm.

FIG. 30. — Outline drawings of the large type nematocysts of Acryptolaria species discussed in the present report. Scale bar: 30 μm.

FIG. 32. — Colony shape and branching in Acryptolaria Norman, 1875: A, A. longitheca (Allman, 1877), from MUSORSTOM 6 stn DW 407; B, A. medeae n. sp., holotype,MUSORSTOM 4 stn CP 195; C, A. niobae n. sp., holotype,BIOCAL 1 stn DW 08; D, A. norfolkensis n. sp., holotype, BIOCAL 1 stn DW 36; E, A. novaecaledoniae n. sp., holotype, MUSORSTOM 6 stn DW 422; F, A. profunda n. sp., holotype, MUSORSTOM 6 stn DW 422; G, A. pseudoangulata n. sp., holotype, MUSORSTOM 4 stn CP 217; H, A. pseudoundulata n. sp., holotype, MUSORSTOM 6 stn DW 457; I, A. pulchella (Allman, 1888), from MUSORSTOM 3 stn DR 117; J, A. pygmaea n. sp., holotype, SMIB 4 stn DW 60; K, A. tetraseriata n. sp., holotype, MUSORSTOM 3 stn DR 117; L, A. undulata n. sp., holotype, BIOCAL 1 stn DW 66. Scale bars: A, C, F-I, 10 mm; B, D, E, K, 20 mm; J, L, 5 mm

FIG. 26.— Acryptolaria pulchella (Allman,1888):A, branch fragment showing hydrothecal arrangement; B, C, hydrothecae; D, part of coppinia (dorsal view);E, part of coppinia showing distal part of gonothecae; A, B, D, E, from MUSORSTOM 3 stn CP 131; C, from MUSORSTOM 3 stn DR 117. Scale bar: A, 600 μm; B-E, 250 μm.