Cryptonome beatrizae, Tovar-Hernández & González-Vallejo & Salazar-Vallejo, 2024

Tovar-Hernández, María Ana, González-Vallejo, Norma Emilia & Salazar-Vallejo, Sergio I., 2024, Cryptonome beatrizae n. sp., from drifting wood in Western Mexico, with remarks on Pareurythoe Gustafson, 1930 (Annelida, Amphinomidae), Zootaxa 5424 (5), pp. 535-553 : 538-541

Cryptonome beatrizae n. sp.

urn:lsid:zoobank.org:act:D254B7D4-1B85-4C08-8391-C75BF3BC254B

Figs 1–4A

Diagnosis. Cryptonome with large eyes, anterior eyes reniform, larger than posterior round to oval ones; median antenna markedly longer than laterals; parapodial cirri pseudoarticulate.

Type material. Eastern Pacific, Gulf of California. Holotype ( ECOSUR 314 ) and 8 paratypes ( ECOSUR 315 ), Sinaloa, Teacapán (22°36’42.58” N, 105°47’35.13” W), on a drift-wood piece (47x 30 cm), 10 May 2021, fixed in 75% ethanol, M.A. Tovar-Hernández, legit.

Additional material. Central Pacific, French Polynesia, Society Islands, Moorea. One specimen ( UF 1536 ), east side of Opunhou Bay (-17.510, -149.851), 0–2 m, rocky shore, in rotten wood, 8 Nov. 2009, fixed in 75% ethanol, T. Lotufo, N. Gravier-Bonnet, A. Anker & J. Norenburg, coll. (complete; left parapodia of chaetiers 15, 40 and 52 removed for observation; body 64 mm long, 2.8 mm wide, 129 chaetigers; other data in remarks) . Two specimens ( UF 1537 ), same data as above (body 11–13 mm long, 2.0– 2.1 mm wide, 43–45 chaetigers; other data in remarks) .

Description.

Holotype (ECOSUR 314) complete, mature female, convolute, broken in two pieces, summing up 109 mm long, 123 chaetigers; anterior fragment 41 mm long, 4.5 mm wide (by chaetiger 10), 44 chaetigers ( Fig. 1A ), removed from a piece of driftwood ( Fig. 4A ); body wall broken laterally, exposing pharynx and anterior gut; posterior fragment 68 mm long, 5 mm wide close to start of fragment, 79 chaetigers.

Body tapered posteriorly, anterior and posterior ends depressed, most body segments swollen; brownish without dorsal pigmentation pattern; venter with a midventral thin dark line ( Fig. 1C ), visible along 60 anterior chaetigers from chaetiger 3, progressively paler. Parapodial cirri, branchiae and chaetae colorless.

Prostomium rounded anteriorly, tapered posteriorly, roughly triangular ( Fig. 1B ). Anterior prostomial lobe rounded, as long as posterior one, separated by a transverse depression; anterior prostomial lobe with tapered lateral antennae, directed anteriorly, surpassing anterior prostomial margin, and palps, about as long as lateral antennae; antennae and palps pseudarticulate. Posterior prostomial lobe with four blackish eyes, anterior eyes reniform, twice wider than posterior, round eyes; median antenna thinner, twice longer than lateral antennae, pseudarticulate, inserted slightly behind posterior eyes, reaching anterior prostomial margin. Caruncle small, cushion-shaped, slightly bent medially, as long as chaetiger 1. Peristomium reduced to two fusiform, longitudinal medially separated cushions; mouth between chaetigers 2–3 ( Fig. 1C ).

Parapodia all biramous, larger anteriorly, progressively smaller along body ( Fig. 2A, B, E ). Notopodia and neuropodia conical, notopodia shorter than neuropodia. Dorsal and ventral cirri tapered; dorsal cirri pseudarticulate ( Fig. 2A , inset), twice longer than ventral cirri; ventral cirri with indistinct annulations.

Branchiae from chaetiger 3, continued along body, missing in last 3–4 chaetigers. Branchial filaments larger, more abundant along chaetigers 10–25, with 6–7 basal stems, and about 120 filaments in anterior chaetigers, 80 filaments in median (chaetiger 56), and 30 in posterior chaetigers (chaetiger 95). Branchial filaments digitate, thinner along anterior region, becoming thicker in median and posterior chaetigers.

Chaetae damaged. Anterior chaetigers with longest notochaetae abundant ( Fig. 2A ), thin serrated capillaries with one row of tiny denticles along one side, 2–3 shorter, thicker bifurcates, and 4–5 spoon-shaped aciculae; longest neurochaetae serrated capillaries, with one row of tiny denticles along one side, 5–6 shorter, thicker bifurcates, and 2–3 spoon-shaped aciculae. Notaciculae with exposed distal part larger than those of neuraciculae. Median and posterior chaetigers with capillaries with darker core ( Fig. 2B, C, E ), without notopodial bifurcates, with additional harpoon-chaetae, longer than bifurcates, shorter than capillaries; basal spur not seen; neurochaetae in median and posterior chaetigers mostly bifurcates, longest tine about 20 times longer than shortest one ( Fig. 2D ).

Posterior end tapered; pygidium with anus terminal, with a distal semicircular lobe; no anal cirri ( Fig. 1D ).

Oocytes visible in coelom from chaetiger 14 (after dissection), more abundant in median and posterior chaetigers; oocytes mostly oval, smooth, about 90–100 μm in diameter along their longer axis ( Fig. 2F ).

Etymology. The species name is derived after Dr. Beatriz Yáñez-Rivera, a very appreciated friend and colleague, in recognition for her studies on amphinomid annelids. The species-group name is a noun in the genitive case ( ICZN 1999, Art. 31.1.2).

Variation. Seven complete paratypes were 17–38 mm long, 2.0– 3.5 mm wide, 58–86 chaetigers. The anterior eyes were reniform in six paratypes, oval in two others, whereas the posterior eyes were round in four paratypes, oval, longer than wide in three others, and triangular to lenticular in another. The median antenna was present in seven paratypes, it was twice longer than laterals in four, and three times longer in the other three. The number of branchial filaments in chaetiger 15 was 35–72, and it was roughly size-dependent because some paratypes were regenerating the anterior region, and sometimes their body shape was slightly distorted during fixation. Only one paratype (36 mm long, 3.5 mm wide, 79 chaetigers) had a thin midventral blackish line along a few anterior chaetigers. The anus was prolapsed in six paratypes, one had it bluish. Bifurcate neurochaetae are present from chaetiger 2–3, continued to the end of body, but most were broken.

Remarks. Cryptonome Borda, Kudenov, Bienhold & Rouse, 2012 includes two groups of species after their parapodial cirri; one group has smooth cirri, whereas the other has pseudarticulate cirri. The second group can be further divided after the length of their median antennae because it can be shorter than the lateral ones such as in C. turcica ( Çinar, 2008) , and another group having their median antennae longer than the lateral antennae, reaching anterior prostomial margin, such as in C. parvecarunculata ( Horst, 1912) , and C. beatrizae n. sp. These two later species differ especially regarding the size of eyes; in C. beatrizae the anterior eyes are larger than the posterior ones, whereas in C. parvecarunculata they are minute, as shown by Çinar (2008: Fig. 6B ), and the author had also indicated that they were of similar size ( Çinar 2008: 1983).

Çinar (2008: 1983) indicated the holotype and some paratypes of C. parvecarunculata had sperm capsules, each about 85 μm in diameter, although there were no illustrations. They might have been oocytes, after their size, and were regarded as sperm capsules instead.

The French Polynesia specimens ( UF 1536 , 1537 ) are regarded as conspecific. The largest specimen ( UF 1536 , Fig. 3A ) matches most features with the holotype described above, although the branchiae are more contracted than in the holotype and do not cover most of the dorsal surface. However, because this variation was also noted in the paratypes, they are regarded as conspecific. This largest specimen ( UF 1536 ) has anterior eyes oval, 3–4 times larger than the posterior ones ( Fig. 3B ), and the variations found in the type material could be explained because the anterior eyes are directed forward ( Fig. 3C ), such that longer periods in ethanol might explain the loss of pigmentation and the changes in shape from oval to reniform.Another slight difference is in the number of branchial filaments along the body; in the Polynesian specimen, there were 50 filaments in chaetiger 15 ( Fig. 3D ) against 60 in a slightly smaller paratype, and 31 in chaetiger 40 ( Fig. 3E ) versus 18 in the same paratype, and a similar size in median chaetigers ( Fig. 3G ), but because a regular size-related trend was not found in the type material, this difference is regarded as a variation without diagnostic relevance. The notochaetae are also similar although the harpoon chaetae have smaller denticles; neurochaetae are bifid with longest tines often broken and can be 3–20 times longer than shortest tines ( Fig. 3F ). The posterior region is tapered with anus dorso-terminal, and branchiae have a few filaments.

Despite the differences in the number (and size) of branchial filaments and the localities where the specimens were found, the populations represented by the specimens we have studied are regarded as conspecific. First, the number of branchial filaments has been shown to vary according to the oxygen saturation level in the environment, as indicated elsewhere ( Ahrens et al. 2013). Second, since Scheltema (1988) seminal study, there are many examples of trans-Pacific dispersal of many marine organisms through their own larvae. Further, marine invertebrates associated with drifting wood have been shown to disperse across the Northern Pacific, from Japan to the United States of America ( Treneman et al. 2018), such that moving from the French Polynesia to Western Mexico is possible as shown elsewhere (Martinez et al. 2009). However, we think that a means to confirm this is through molecular analysis which are beyond our current objectives.

Figures

FIGURE 1. Cryptonome beatrizae n. sp., holotype (ECOSUR 314). A. Anterior region, dorsal view (LA, lateral antenna; Pa, palp; numbers indicate chaetigers). B. Anterior end, dorsal view, after Methyl Green staining (Ca, caruncle; LA, lateral antenna; MA, median antenna; Pa, palp; numbers indicate chaetigers). C. Anterior end, ventral view. D. Posterior region, dorsal view. Scale bars: A, 0.6 mm; B & D, 0.4 mm; C: 0.5 mm.

FIGURE 2. Cryptonome beatrizae n. sp., holotype (ECOSUR 314).A. Chaetiger 14, left parapodium, anterior view (inset: closeup of dorsal cirrus). B. Chaetiger 56, left parapodium, anterior view. C. Same, close-up showing basal darker notochaetal cores. D. Paratype 5, chaetiger 30, left parapodium, neurochaetae (inset: neuraciculae). E. Holotype, chaetiger 95, left parapodium, anterior view (inset: close-up of notochaetal darker cores). F. Oocytes. Scale bars: A, 0.38 mm; B, 0.41 mm; C, 0.1 mm; D, 15 μm; E, 0.37 mm; F, 30 μm.

FIGURE 3. Cryptonome beatrizae n. sp., non-type specimen (UF 1536). A. Anterior region, dorsal view (pa, palp; numbers indicate chaetigers). B.Anterior end, after Methyl-Green staining, dorsal view (MA, median antenna; Pa, palp; numbers indicate chaetigers). C. Same, frontal view. D. Chaetiger 15, left parapodium, posterior view. E. Chaetiger 40, left parapodium, posterior view. F. Same, tips of neurochaetae and neuracicula. G. Chaetiger 52, left parapodium, posterior view. H. Posterior region. Scale bars: A, 0.6 mm; B, D, 0.4 mm; C, 0.3 mm; E, G, 0.5 mm; F, 45 µm; H, 0.8 mm.

FIGURE 4. Cryptonome beatrizae n. sp. and associated fauna. A. Piece of wood with the holotype in a gallery. B. Fragments of bored wood. C. Anadara labiosa (Sowerby, 1833). D. Teredinid tube with sediment inside it. E. Unidentified barnacle. F. Unidentified hydroids. Scale bars: A, 4 mm; B, 7 mm; C, 1 mm; D, 5 mm; E, 0.5 mm; F, 0.3 mm.

FIGURE 6. Cryptonome americana (Hartman, 1951) n. comb., paratype (LACM 103). A. Anterior region, dorsal view, after Shirlastain-A. B. Anterior end, dorsal view, after Methyl Green staining (numbers indicate dorsal cirri). C. Chaetiger 40, right parapodium, anterior view. D. Same, tips of furcate neurochaetae. E. Posterior region, oblique right lateral view. Scale bars: A, C, 0.5 mm; B, 0.3 mm; D, 150 µm; E, 0.8 mm.