Hyalopale zerofskii Watson, Tilic & Rouse, 2019

Cruz-Gómez, Christopher, 2021, A new genus and seven new species of chrysopetalids (Annelida, Chrysopetalidae) from the Tropical Eastern Pacific, Zootaxa 5068 (1), pp. 1-59 : 17

Hyalopale zerofskii Watson, Tilic & Rouse, 2019

Figs 8 , 12

Hyalopale zerofskii Watson, Tilic & Rouse, 2019: 349 , Figs 1F , 5A–F , 6A–G .

Hyalopale sp. — Cruz-Gómez & Bastida-Zavala 2018: 75–76, Figs 9A–I , 13 , 14I , 15F . — Cruz-Gómez et al. 2021: 183, Fig. 5S (key of chrysopetalids from Tropical America).

Type locality: San Clemente Island , California, USA ( Watson et al. 2019) .

Material examined. ECOSUR-2998 , Bahía de los Ángeles, Baja California, México, northern Mexican Pacific, 1 m, February 24, coll . SSV.

Description. Based on the only specimen found: complete but fragmented with 14 segments. TL= 0.9 mm, TW= 0.3 mm. Body short, broad, truncated posteriorly ( Fig. 8A ). Body whitish. Paleae fan translucent, slightly imbricated dorsally.

Prostomium barely visible among the first three segments. Lateral antennae, short, inserted on the antero-ventral prostomial margin, median antenna slightly shorter than lateral ones. Eyes red-violet, two pairs, anterior pair massive. Nuchal organ not present ( Fig. 8B ). Palps short, oval, visible in ventral view. Mouth fold small, placed between segment 2 and 3. Pharynx muscular and eversible, not exposed, stylets slender.

Parapodium from segment 5, notochaetae in two main groups ( Fig. 8D ). Notochaetae: lateral spine curved, without internal ribs ( Fig. 8E ). Main group, 10–12 paleae; lateral-most palea broad and asymmetrical with 16–20 internal ribs ( Fig. 8F ); mid-most palea curved and asymmetrical with (20) 24–26 (27) internal ribs ( Fig. 8G ); midline-most palea shorter, slender and asymmetrical with 14–18 internal ribs ( Fig. 8H ). Median spine absent. All paleae with hooked tips, rounded brow, margins serrated, and denticles on internal ribs.

Neuropodium conical, longer than notopodium. Neurochaetae: unit 1, 5–8 superior spinigers, blades straight and long, 10–12 times longer than wide ( Fig. 8I ). Unit 2, 5–6 falcigers, blades straight and medium-sized, 6–7 times longer than wide ( Fig. 8J ). Unit 3, 5 falcigers, blades straight and medium-sized, 5–6 times longer than wide ( Fig. 8K ). Unit 4, 2 falcigers, blades curved and short, 4–5 times longer than wide ( Fig. 8L ). Pygidium rounded, with two long anal cirri ( Fig. 8C ). Oocytes not seen.

Habitat. Intertidal to subtidal (1 m). Specimens of this species have been collected on algae Padina and rumble coral ( Cruz-Gómez & Bastida-Zavala 2018; Watson et al. 2019).

Distribution. From San Clemente Island, California, to Bahía de los Ángeles, Baja California and Estacahuite Bay, Oaxaca ( Fig. 12 ). According to Watson et al. (2019), there is a specimen that possibly belongs to H. zerofskii from French Polynesia; morphological differences were noticed and described then, despite these differences it was still considered part of the H. zerofskii ‘species complex’.

Remarks. Recently Watson et al. (2019) described H. zerofskii from California, previously recorded as Hyalopale sp. (sensu Cruz-Gómez & Bastida-Zavala 2018: 75) from Oaxaca, and so far, this is the only Hyalopale species known on from the Pacific coast of America.

The specimen identified here agrees with H. zerofskii however, some differences were noted. The internal ribs in main paleae vary in number along the species distribution: 25–26 (27) in specimens from California ( Watson et al. 2019), 24–26 (27) in specimens from Gulf of California, and 21–25 (27) in specimens from the southern Mexican Pacific ( Cruz-Gómez & Bastida-Zavala 2018). Further, raised ribs are notorious in small immature specimens ( Cruz-Gómez & Bastida-Zavala 2018); in adult specimens, as those revised here, raised ribs are shallow and only noted by having large denticules on their surface. Regarding neurochaetae, here they were illustrated in detail and lead to note some differences from those in small specimens, the main difference is related to their blade length. Adult specimens have neurochaetal blades from all units with relatively the same length as unit 1 blades, whereas small immature specimens have blades with a distinct length according to their dorso-ventral position ( Cruz-Gómez & Bastida-Zavala 2018: Fig. 9B–E ).

Figures

FIGURE 1. Study area. The Tropical Eastern Pacific, and southmost part of Warm Temperate Northern Pacific, with the names of the main localities.

FIGURE 5. Paleanotus karlyae n. sp., holotype (ECOSUR-258). A) Complete fragmented body. B) Drawing of prostomium, dorsal view. C) Drawing of pygidium, ventral view. D) Parapodium from segment 23. E) Lateral paleae. F) Subunit 1. G) Main palea. H) Apex of G. I–J) Median paleae. K) Unit 1. L) Unit 2. M) Unit 3. N) Unit 4. Scales: 10 µm (KLMN), 20 µm (CEFH), 50 µm (IJ), 100 µm (B), 200 µm (D), 500 µm (A).

FIGURE 6. Paleanotus sp., non-type specimen (UMAR-Poly-017). A) Fragments. B) Parapodium from middle segment; B) Lateral paleae; C) Main palea; D–F) Median paleae; G–H) Unit 1; I) Unit 2; J) Unit 3; K) Unit 4; L) Pygidium, ventral view. Scales. Scales: 10 µm (HIJK), 20 µm (CDEFG), 100 µm (AB).

FIGURE 8. Hyalopale zerofskii Watson, Tilic & Rouse, 2019, non-type specimen (ECOSUR-2998). A) Complete fragmented body, arrow indicates anterior segments. B) Drawing of prostomium, dorsal view. C) Drawing of pygidium, ventral view. D) Parapodium from segment 5. E) Lateral spine. F) Main palea, lateral-most. G) Main palea, mid-most. H) Main palea, midlinemost. I) Unit 1. J) Unit 2. K) Unit 3. L) Unit 4. Scales: 10 µm (C), 20 µm (BIJKL), 50 µm (DEFGH), 100 µm (A).

FIGURE 9. Arichlidon mucropaleum n. sp., holotype (ECOSUR-260). A) Complete fragmented body. B) Drawing of prostomium, dorsal view. C) Drawing of pygidium, ventral view. D) Parapodium from segment 22. E) Lateral paleae, arrow indicates wide palea. F) Main palea. G) Subunit1. H) Median palea, mid-most. I) Median palea, proximal-most. J) Unit 1. K) Unit 2. L–M) Unit 3. N–P) Unit 4. Scales: 50 µm (BCEFGHIJKLMNO), 200 µm (D), 1 mm (A).

FIGURE 12. Previous and new records of chrysopetalids in the Tropical Eastern Pacific. Empty symbols indicate historic records.

FIGURE 13. Paleaequor psamathe Watson Russell, 1986, non-type specimen (ECOSUR-3068). A) Complete body. B) Drawing of prostomium, ventral view. C) Drawing of pygidium, ventral view. D) Oocyte. E) Parapodium from segment 15. F) Lateral paleae. G) Subunit 1, two kinds of paleae. H) Main paleae. I) Median paleae. J) Unit 1. K) Unit 2. L) Unit 3. M–N) Unit 4. Scales: 10 µm (JKLMN), 50 µm (BCFGHI), 200 µm (E), 2 mm (A).

FIGURE 14. Bhawatsonia fusa n. sp., holotype (ECOSUR-263). A) Complete fragmented body. B) Drawing of prostomium, dorsal view. C) Drawing of prostomium, ventral view. D) Prostomium, dorsal view. E) Prostomium, ventral view; arrow indicates Mo. F) Right side of middle segments, arrow indicates dorsal cirrus. G) Dorsal side of the specimen, showing the middorsal line paleae free. H) Parapodium from segment 49. I) Lateral paleae. J) Subunit 1. K) Main palea, arrow indicates finely raised rib. Scales: 20 µm (IJK), 100 µm (BCDEFH), 500 µm (G), 1 mm (A).

FIGURE 15. Bhawatsonia fusa n. sp., holotype (ECOSUR-263). A–B) Median paleae. C) Unit 1. D) Unit 2. E–F) Unit 3. G) Unit 4. H) Pygidium, ventral view. I) Complete body, largest specimen (ECOSUR-3219). Scales: 10 µm (CDEFG), 20 µm (AB), 50 µm (H),1 mm (I).