Aponuphis ornata ( Fauvel, 1928 )

Arias, Andrés & Paxton, Hannelore, 2015, Onuphis and Aponuphis (Annelida: Onuphidae) from southwestern Europe, with the description of a new species, Zootaxa 3949 (3), pp. 345-369 : 361-363

Aponuphis ornata ( Fauvel, 1928)

Figures 7 D–H, 8, 9

Hyalinoecia bilineata ornata Fauvel, 1928: 12 . Morocco; 1936: 52, fig. 3 ( Morocco); 1938: 15 (Venice Lagoon, Adriatic Sea). Aponuphis ornata . — Paxton 1986: 54 (new combination).

Material examined. Type material. Two syntypes of Hyalinoecia bilineata ornata Fauvel, 1928 (MNHN-IA- TYPE 0815 and MNHN-IA-TYPE0816) “Vanneaux” sta. CXIX and LVI, Morocco.

Non-type material. Three specimens ( MNHN) “Vanneaux” sta. XLIII, Marocco; 14 specimens ( MNCN 16.01/ 3881- MNCN 16.01/3883, MNCN 16.01/3895) off shore between Vidio Cape and Peñas Cape, Cantabrian Sea, Spain, 15–32 m, 5 Apr 1998; 88 specimens ( MNCN 16.01/1828- MNCN 16.01/1830, MNCN 16.01/1833, MNCN 16.01/1835, MNCN 16.01/1837- MNCN 16.01/1838, MNCN 16.01/1841, MNCN 16.01/1843, MNCN 16.01/ 2158- MNCN 16.01/2163, MNCN 16.01/2165, MNCN 16.01/2168, MNCN 16.01/2170- MNCN 16.01/2173, MNCN 16.01/2175- MNCN 16.01/2180, MNCN 16.01/2672) off shore between San Antonio cape and Valencia harbour, E. Spain, western Mediterranean, 3–30 m, 26 Apr 1996; 2 specimens ( MNCN 16.01/7820) off shore between Olympic Port of Barcelona and Mataró, NE. Spain, western Mediterranean, 5–25 m, 1 Jan 2000; 6 specimens ( MNCN 16.01/8805) off shore Punta Torrox, E. Spain, Alborán Sea, western Mediterranean, 3–30 m, 17 Apr 2002.

Comparative material. Two syntypes of Hyalinoecia grubii ( NHMW 1169) Saint-Malo, France, collected in 1883.

Type locality. Coast of Morocco, East Atlantic.

Diagnosis. Antennae usually to chaetiger 10, maximally to 16; four to six ceratophoral rings on median antenna, usually seven to ten on lateral antennae, maximally 11. Anterior three to five chaetigers with several tridentate pseudocompound hooks (rarely tri- and quatridentate), chaetigers 4–6 with one hook only; slender longappendaged hooks present. Ventral cirri subulate on first five chaetigers. Subacicular hooks from chaetiger 10. Branchiae from chaetiger 3 to 4. Colour pattern consisting of orange to light brown transverse bands and spots varying according to body region. Peristomium with two large dorsal spots, sometimes coalescing medially; first chaetigers with two wide bands separated medially (one close to anterior end of segment and other close to posterior edge), presenting four bars; following chaetigers with one solid band anteriorly and two bars posteriorly, bars and bands ranging from relatively narrow ( Fig. 7 D) to wide ( Fig. 7 E) and two segmental lateral spots from chaetiger 1 to posterior region; sometimes posterior bands displayed medially on segment, appearing as more or less quadrangular spots. Other specimens with more complicated pattern as consequence of fusion of anterior and posterior segmental bars ( Fig. 7 F). More posteriorly, anterior and posterior bars (or posterior quadrangular spots) getting closer and merging into single wide transversal band per segment. Maximum width without parapodia 1.4 mm.

Remarks. Hyalinoecia bilineata ornata was described by Fauvel (1928) as differing from the stem species by its colour pattern. However, H. bilineata ornata differs also in parapodial and chaetal features from A. bilineata . We have examined the syntypes of Hyalinoecia bilineata ornata and found them to have only tridentate (not bi- and tridentate) hooks, less anterior parapodia with hooks and shorter antennae than A. bilineata . The colour pattern of the syntypes was not preserved but we examined specimens from a different station taken by the “Vanneaux” that clearly displayed the typical pigmentation of the species. Aponuphis ornata is very similar to Aponuphis grubii (Marenzeller, 1886) . The two species have basically the same colour pattern except that the bars and lines are substantially wider and appear overall more strongly pigmented in the former than in the latter. The antennae of A. ornata are longer and its branchiae occur from chaetiger 3–4 instead of 4–5. Their reproductive methods are very different. As we are detailing below, A. ornata is a brooder with direct development, while A. grubii is a broadcast spawner with lecithotrophic larvae as has been reported by Rivain (1983) for the Rance population in northern France (as Hyalinoecia bilineata ). On the basis of the data we have so far, we consider A. grubii as a northern European species. It is common in the Normano-Breton Gulf and may be restricted to the English Channel. In contrast, A. ornata is a southern species that occurs from the Bay of Biscay to Morocco, including the western and central Mediterranean.

Biology. Among the samples from the Cantabrian shelf, one specimen was collected in its tube together with eight vermiform juveniles, and one specimen from the Mediterranean with two juveniles. The juveniles range from 2.0– 4.1 mm in length for 15–38 chaetigers and measure 0.3–0.6 mm in width, with the largest presenting a colour pattern on the dorsum of the anterior chaetigers ( Figs 7 H). All juveniles have well developed frontal lips, palps and antennae, the ceratophores of the largest two with three to four rings. The parapodia are well developed with dorsal cirri on the first seven to 10 chaetigers and subulate ventral cirri on the first two. Branchiae are absent; the pygidium bears two pairs of slender anal cirri. In addition, six recently settled juveniles were dredged from a depth between 3 to 30 m in Málaga (southern Spain). The specimens range from 4.2–7.1 mm in length for 44–52 chaetigers and measured 0.45–0.55 mm in width. These specimens have a well pigmented colour pattern ( Fig. 7 G) and the three larger ones have branchiae from chaetiger 7–9 to 15.

The chaetal composition of juveniles ( Fig. 8 ) differs from that of adults and has been detailed for these A. ornata specimens in Fig. 9. The smallest juveniles examined have four compound hooks in the first two pairs of parapodia. In the 15-chaetiger specimen they are only bidentate ( Fig. 8 B) and the 17- and 23-chaetiger specimens have bi- and tridentate hooks ( Figs 8 A, B). Parapodia 3–8 have two limbate chaetae and two kinds of anterior provisional subacicular hooks (SAHs): one with a large appendage in the medial position of the parapodium ( Fig. 8 C) and two ventral hooks with small appendages ( Fig. 8 D). Two permanent SAHs start on chaetiger 9, being present to chaetiger 12–14, when one of these, and a few chaetigers later both are replaced by posterior provisional subacicular hooks ( Fig. 8 E). Pectinate chaetae are absent.

The 28- and 38-chaetiger juveniles have bi- and tridentate compound hooks on the first three parapodia; parapodia 2 and 3 with four hooks and parapodium 3 with only one bidentate hook and two limbates. The anterior provisional hooks are now restricted to chaetiger 4 only, with chaetigers 5–8 lacking any hooks, having only limbate chaetae. Two permanent SAHs are present from chaetiger 9–20 or 22 when first one, and then both permanent SAHs are replaced by posterior provisional SAHs. A flat pectinate chaeta with 10–11 teeth is present from chaetiger 19 to 20–22.

The recently settled juveniles have four chaetigers with compound hooks, lack anterior provisional SAHs, have permanent SAHs from chaetiger 9–10 to 29, when they are replaced by posterior provisional SAHs.

The branchial development commences when juveniles consist of about 40 chaetigers. The branchiae start on chaetiger 7–9, from there they spread more posteriorly but also anteriorly, passing through intermediate forms with branchiae starting on chaetiger 6 and 5. When the worm has attained about two-thirds of its maximum size the branchiae begin on chaetiger 3–4 which is considered here as the adult condition of the species.

Distribution. East Atlantic (Bay of Biscay and Atlantic Iberia) and western and Central Mediterranean Sea. Previous records of A. grubii (or H. bilineata grubii ) from the Iberian coasts and the Mediterranean most likely correspond to A. ornata .

Figures

FIGURE 7. Aponuphis spp. photomicrographs showing its characteristic colour patterns. A, A. bilineata morph 1 (typical); B. A. bilineata morph 2; C, A. brementi; D – E, A. ornata; G, recently settled juvenile of A. ornata; H, brooding juvenile of A. ornata.

FIGURE 8. Aponuphis ornata. Line drawings of juvenile hooks. A, tridentate compound hook; B, bidentate compound hook; C, median anterior provisional subacicular hook; D, ventral anterior provisional subacicular hook; E, posterior provisional subacicular hook.