Hyalopale, Perkins, 1985

Cruz-Gómez, Christopher & Bastida-Zavala, J. Rolando, 2018, Chrysopetalids (Phyllodocida: Chrysopetalidae) from the southern Mexican Pacific, including a new species, Zootaxa 4521 (1), pp. 61-88 : 75-76

Hyalopale sp.

( Figures 9 A–I, 13, 14I, 15F)

Material examined. Oaxaca: UMAR-Poly 911, four spec.; MAGNT s.n., one spec. ( Estacahuite Bay , 15°40’05’’N, 96°28’53’’W, Oaxaca, on Padina sp., 2–4 m, August 25, 2007)

Description. Based mainly on largest complete animal, 0.8 mm long, 0.3 wide, 13 segments. Body very small, rectangular, pale yellow to orange. Paleae fans yellow to golden, imbricated over dorsum. Prostomium visible among the first two anterior segments. Two small lateral antennae partially visible on anterior margin of prostomium; a subulate median antenna, larger than lateral antennae (about three times lateral antenna length). Two pairs of violet eyes, first pair smaller than second; in some specimens the eyes are jointed longitudinally, making the ocular spot seems rectangular. Nuchal fold absent. Two palps almost circular, visible in ventral view. Muscular and circular mouth fold posterior to palps; eversible proboscis with two short and slim transparent stylets.

Parapodium from the ninth segment. Notochaetae separated in three main groups and one subgroup ( Fig. 9A ). Lateral group inserted just below of notoaciculum; including one slender curved spine without ribs ( Fig. 9F ). As sub-unit 1, one almost symmetrical and slightly serrated palea with 16–22 ribs and four raised ribs ( Fig. 9G ). Main group, comprising 9–12 wide, long and asymmetrical paleae with 21–28 ribs and 4–6 raised ribs finely serrated ( Fig. 9H ). When present, median group comprising one curved and almost symmetrical paleae, with 15–18 ribs and 5–6 raised ribs ( Fig. 9I ). Every paleae in these groups showing a serrated edge and a hooked final tip, except for the lateral group. Neuropodium small and cylindrical. Heterogomph neurochaetae composed of four groups ( Fig. 9 B– E). Neurochaetigers with 2–3 superior spinigers, with long, slim curved blades. Presence of superior spinigers increasing in the first three segments. Mid-superior group with 7–9 falcigers with medium length blades (2/3 of spiniger blade length) and serration basally. Mid-inferior group with 6–8 falcigers with medium to short blades (1/2 of spiniger blade length), serration basally. Inferior group of 2–4 falcigers with short and smooth blades (2/7 of spiniger blade length) with fine serration basally. Every blade of falcigers ending in a terminal claw. Pygidium rounded, with two reduced anal cirri.

Habitat. Subtidal (2–4 m). These specimens were collected on algae ( Padina sp.).

Distribution. Southern Mexican Pacific, only known from Estacahuite Bay, Oaxaca ( Fig. 13 ).

Remarks. Hyalopale sp. has a small fragile body. The largest complete specimen has 13 segments. Hyalopale sp. differs from H. bispinosa Perkins, 1985 , described from Florida, in having a smaller body than the latter (approximately two millimeters); Hyalopale sp. presents only one spine in the lateral group of paleae, while H. bispinosa usually has more than one spine in the mid-line and lateral group; also, the shape of the superior spinigers in Hyalopale sp. is curved and smooth, while in H. bispinosa it is straight and serrated ( Perkins 1985: 910, Fig. 29H). Currently this morphospecies is being described from southern California specimens (Watson, pers. comm. 2017).

Figures

FIGURE 9. Hyalopale sp. A, parapodium middle segment; B–E, neurochaetal types; F, lateral palea (spine); G, subunit 1 palea; H, main palea; I–K, median palea. Scale bars: 20 µm (BCDEF), 30 µm (GHI), 100 µm (A).

FIGURE 13. Historical and new records of Hyalopale sp., Paleaequor psamathe, Paleanotus bellis and P. purpurea. Empty symbols indicate previous records.