Paleaequor nicoyensis Watson Russell, 1986

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 : 24-26

Paleaequor nicoyensis Watson Russell, 1986

Figs 11 , 12

Paleaequor nicoyensis Watson Russell, 1986: 170–172 , Figs 25 –28.

Type locality: Gulf of Nicoya , Costa Rica, on sand at 44 m ( Watson Russell 1986) .

Material examined. Seven specimens. Costa Rica: Two spec. Puntarenas: UMAR-Poly-OH-018, cruise pier, on pier piles, 1.5 m, November 22, 2012, coll. TVG. Guanacaste: UMAR-Poly-OH-027, Cabuyal beach, on dead coral, 0.5 m, November 3, 2012, coll. TVG. Perú: Five spec. Piura: UMAR-Poly 953, 3 spec. Vichayo , 5°47´56”S, 80°56´48”W, on shells, 0.5 m, 2014, coll. IC. Tumbes: UMAR-Poly 954, 2 spec. Corvina , 3°62´76”S, 80°70´76”W, in mud, 15 m , 2012.

Description. Based on the best-preserved specimens (UMAR-Poly 954): complete with 57 segments. TL= 6.3 mm, TW= 0.8 mm. Body long, slender, tapered posteriorly ( Fig. 11A ). Body pale orange. Paleae fan translucent, imbricated dorsally.

Prostomium visible among the first four segments. Lateral antennae short, inserted on the antero-ventral prostomial margin, median antenna about the same length of lateral ones, inserted in front of the first pair of eyes. Eyes red-violet, two pairs. Nuchal organ, small, partially covering the prostomium ( Fig. 11B ). Palps long, cylindrical, visible in ventral view. Mouth fold small, placed between segment 2 and 3. Pharynx eversible, not exposed, stylets thick.

Parapodium from segment 20, notochaetae in three main groups ( Fig. 7E ). Notochaetae: lateral group inserted below notaciculum, 2–6 paleae, slender and symmetrical, with 5–8 internal ribs ( Fig. 11E ); subunit 1, 1 palea, slender and symmetrical, with 9–15 internal ribs, and margins finely serrated ( Fig. 11F ). Main group, 20–26 paleae, broad and symmetrical, with (14) 16–19 internal ribs, and 4–5 raised ribs ( Fig. 11G ). Median group, 3–4 paleae shorter, broad, symmetrical, with (12) 13–20 internal ribs and 2–4 raised ribs ( Fig. 11H ).

Neuropodium conical, slightly longer than notopodium. Neurochaetae: unit 1, 2–4 superior spinigers, blades straight and long, 12–14 times longer than wide ( Fig. 11I ). Unit 2, 2–4 falcigers, blades straight and medium-sized, 6–7 times longer than wide ( Fig. 11J ). Unit 3, 4–5 falcigers, blades straight and medium-size, 4–5 times longer than wide ( Fig. 11K–L ). Unit 4, 2–3 falcigers, blades straight and short, 3 times longer than wide ( Fig.11M ). Pygidium rounded with two anal cirri, and a reduced ventral cone ( Fig. 11C ). Oocytes not seen.

Habitat. Intertidal to subtidal (0.5– 15 m). Specimens of P. nicoyensis were collected in mud, shells, dead coral, among the fouling communities; also, previously recorded on coarse sand ( Watson Russell 1986).

Distribution. From Gulf of Nicoya, Costa Rica to Corvina, Perú ( Fig. 12 ).

Remarks. Examined specimens of P. nicoyensis agree with the original description by Watson Russell (1986); however, intraspecific differences were detected. Specimens from Perú have a lower number of paleae on every group of paleae, possibly associated with the size, since these specimens were smaller than those collected from Costa Rica.

Figures

FIGURE 7. Treptopale watsonae (Cruz-Gómez & Bastida-Zavala 2018), non-type specimen (UMAR-Poly 935). A) Complete fragmented body, arrow indicates anterior end. B) Drawing of prostomium, dorsal view. C) Drawing of pygidium, ventral view. D) Oocyte. E) Parapodium from segment 22. F) Lateral paleae, arrow indicates subunit 1. G) Main palea. H–I) Median paleae. J) Unit 1. K) Unit 2. L) Unit 3. M) Unit 4. Scales: 5 µm (D), 50 µm (BCFGHIJKLM), 200 µm (E), 500 µm (A).

FIGURE 11. Paleaequor nicoyensis Watson Russell, 1986, non-type specimen (UMAR-Poly 954). A) Complete body. B) Drawing of prostomium, ventral view. C) Drawing of pygidium, ventral view. D) Parapodium from segment 20. E) Lateral paleae. F) Subunit 1. G) Main palea. H) Median palea. I) Unit 1. J) Unit 2. K) Unit 3. L–M) Unit 4. Scales: 20 µm (EFGHI- JKLM), 50 µm (BC), 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 25. Apex of main paleae of some Chrysopetalum species from the Tropical Eastern Pacific, and the southernmost part of Warm Temperate Northeast Pacific. Chrysopetalum elegantoides Aguado, Capa & San Martín, 2003 (ECOSUR-3001). A) Main palea, lateral-most. B) Schematic of A. C) Schematic of D. D) Main paleae, midline-most. Chrysopetalum mexicanum n. sp. (ECOSUR-270). E) Main palea, lateral-most. F) Schematic of E. G) Schematic of H. H) Main paleae, midline-most. Chrysopetalum tovarae n. sp. (ECOSUR-273). I) Main palea, lateral-most. J) Schematic of I. K) Schematic of L. L) Main paleae, midline-most.