Hyalopale Perkins, 1985

Watson, Charlotte, Tilic, Ekin & Rouse, Greg W., 2019, Revision of Hyalopale (Chrysopetalidae; Phyllodocida; Annelida): an amphi-Atlantic Hyalopale bispinosa species complex and five new species from reefs of the Caribbean Sea and Indo-Pacific Oceans, Zootaxa 4671 (3), pp. 339-368 : 343

Genus Hyalopale Perkins, 1985

Type species. Hyalopale bispinosa Perkins, 1985

Diagnosis. Small bodied chrysopetalids, as adults <3 mm in length, attaining maximally 20 segments. Dorsum covered in asymmetric-shaped, transparent main paleae with multiple stacked internal ribs; lateral spines present, midline spines present or absent. Prostomium fused with anterior segments, with two pairs of large complex eyes, median and lateral antennae, moderate-sized oval palps. Achaetous segment I with pair of dorsal and ventral cirri (= tentacular cirri); segment II with pair of dorsal cirri, notochaetae, neurochaetae, ventral cirri absent. Pharynx with pair of stylet jaws. Pygidium a shallow lobe with two small anal cirri.

Description. Small-bodied, rectangular, tapered a little at posterior end, dorsum covered with hyaline, petaloid paleae fans, long-shafted falcigerous neurochaetae extend out beyond notopodia ( Fig. 7 ). Prostomium a shallow, broad lobe not well-defined, with 2–3 pairs of large, bright red to maroon coloured eyes, often overlapping. Fingershaped median antenna inserts on anterior edge of prostomium, anterior to two slender lateral antennae, two ovoid palps insert ventrally ( Fig. 5C, D ). Muscular pharynx with small calcified pharyngeal ring, single pair of short stylet jaws with broad, inner groove, tanned distal jaw tips ( Figs 4C ; 5B ). Segment 1 very reduced, with one pair slender, dorsal, ventral cirri; ventral pair adjacent to palps. Segment II notopodia with notochaetal spines only, dorsal cirri; neuropodia with spinigerous neurochaetae, ventral cirri absent. Segments II–III fused in part ( Figs 5B ; 10A, B ). Mid-body notopodium with short, very slender aciculum, slender dorsal cirrus 1/2 to 2/3 length of main paleal fan; sub-acicular lateral notochaetal group composed of single spine, slightly curved with slight serrate margins, attenuated tip, inserts overlying aciculum. Main paleae notochaetal group composed of long, asymmetrical paleae with rounded or sloping brow, finely dentate convex margin, very small apices, numerous very fine internal ribs stacked close together, usually includes very shallow raised ribs. Midline spines present or absent ( Figs 3 ; 4E ; 8A ).

Mid-body neuropodium with long, slender aciculum. Subacicular falcigerous neurochaetae with long shafts, comprising superior group with longest, very slender blades, minutely serrate, with minute curved distal tips; middle group with longer basal serrations to blades; inferior group short, slender bladed ( Fig. 9D ). Pygidia with very short to slightly longer filiform pair of anal cirri ( Fig. 4B ).

Remarks. Hyalopale is one of two chrysopetalid genera (also Treptopale ), erected by Perkins (1985) from Florida coral reefs. Hyalopale and Treptopale are morphologically close to Paleanotus , with similar anterior end configurations and chaetal types ( Perkins 1985; Watson 2010; Watson 2015), and similar stylet jaws ( Watson & Faulwetter 2017). Hyalopale is distinguished primarily by its small adult size and by the presence of spines in the lateral and midline positions in the notochaetal fascicle, which in Treptopale and Paleanotus are represented by developed paleal fascicles. Hyalopale has an extremely small adult size (length 1–2.8 mm, segments <20) a simple body, and possesses very thin, hyaline main group paleae with a multiplicity of internal ribs finely stacked together. Hyalopale adult morphology is similar to larvae of other paleate chrysopetalids, which is described in more detail at the end of this paper.

Figures

FIGURE 3. Hyalopale leslieae sp. nov. Florida Keys, Paratype USNM1490841, chaetal types of right and part left mid-body notopodia; inset: midline-most main palea.

FIGURE 4. H. leslieae sp. nov. A–E Belize, micrographs, specimen photographed before sacrifice for DNA; A. live, dorsal view, entire body; B. pygidium with anal cirri; C. dorsal view, anterior end; D. lateral view, detail of main paleae & internal ribs; E. mid-body, notochaetal fan.

FIGURE 5. H. zerofskii sp. nov., A–F, San Clemente Is. California, Paratypes, SIO-BIC A8083. A. live, colour stereo micrograph, ovigerous female; B–F. micrographs. B. anterior end, dorsal; C. anterior end, dorsal; D. anterior end, ventral; E. midbody notopodium in part with glands; F. detail of dorsal cirri with cilia.

FIGURE 7. H. sapphiriglancyorum sp. nov. Raja Ampat, Indonesia, Paratypes, MZB Poly. 00410, live, colour stereo micrograph, gametous individuals.

FIGURE 8. H. sapphiriglancyorum sp. nov. Raja Ampat, Indonesia, Paratype, MZB Poly. 00410, A. mid-body notopodium with detail of main palea.

FIGURE 9. H. angeliensis sp. nov. A,C. Dampier, Western Australia, Holotype, AM W.36166 A. detail middle group palea, C. detail of midline-most main paleae; B,D. Seychelles, USNM 1076948. B. detail middle group palea, D. neurochaetal falcigerous types from mid-body segment, left to right: superior very long bladed, mid-superior long bladed, mid-group broader bladed with larger serrations, inferior group short bladed.

FIGURE 10. H. furfuricula sp. nov. Red Sea, Holotype, NTM W.25602. A. anterior end, dorsal view; B. ventral view.