Hesione pantherina Risso, 1826

Salazar-Vallejo, Sergio I., 2018, Revision of Hesione Savigny in Lamarck, 1818 (Annelida, Errantia, Hesionidae), Zoosystema 40 (12), pp. 227-325 : 283-286

Hesione pantherina Risso, 1826 , restricted

( Figs 35 , 36 )

Hesione pantherina Risso, 1826: 418 , 419. — Audouin & Milne Edwards 1833: 234, 235, pl. 15, fig. 4. — Fauvel 1914: 121, 122; 1923a: 233, 234, fig. 87 (partim); 1932b: 20 (Toulon); 1934: 21; 1950: 349. — Fauvel & Rullier 1957: 36; 1959b: 512.

Fallacia pantherina – Quatrefages 1866: 98, 99. — Malaquin 1894: 417.

Hesione splendida – Campoy 1982: 208-210, pl. 11, figs A-D. — Kirkegaard 1983: 213. — Sordino 1990: 35. — Brito et al. 1996: 163, fig. 5A-C. — Parapar et al. 2004: 216, fig. 76 (partim, non Savigny in Lamarck, 1818).

TYPE MATERIAL. — Mediterranean Sea, France. Neotype, MNHN- IA-TYPE1850 (formerly jar 70.190b), Mer de Nice , labeled in 1868, no further data. 2 specimens labelled paraneotype: MNHN-IA- TYPE 1851 (formerly jar 70.190c), Mer de Nice, no further data; MNHN-IA-TYPE1852 (formerly jar 70.190d), mer de Nice, no further data [54 mm long, 7 mm wide; body distorted by compression in small container, especially anterior end; most parapodial lobes invaginated, once exposed, all with acicular lobe single; neuraciculae black, subdistally expanded, mucronate].

ADDITIONAL MATERIAL. — Mediterranean Sea. Argelia. 3 specimens, MNHN-IA-PNT91j (formerly jar 70), 1900, no further data, M. Pallary coll. [25-38 mm long, 3-4 mm wide; two slightly macerated; acicular lobes single, neuraciculae blackish tapered, distally swollen, mucronate] .

France. 1 specimen, SMF 15475, Gulf of Marseille , Pointe Donnelle, Sta. A4 H, 2.XI.1982, A. Willsie coll. [17 mm long, 2 mm wide; colorless, bent ventrally, all dorsal and tentacular cirri lost, left parapodium of chaetiger 10 removed for observation (kept in vial); pharynx partially exposed, dorsal papilla not seen; antennae digitate, 2-3 times as long as wide; eyes barely pigmented, anterior ones twice as large as posterior ones; acicular lobe single, blunt; neurochaetal blades bidentate, subdistal tooth smaller, guards mostly broken, if entire, approaching distal tooth] .

Undefined locality. 2 specimens, ZMB 3812 , Grube Collection , Dr Bergmann coll., no further data [44-48 mm long, 6-8 mm wide; a few parapodia previously removed and set into permanent slides; smaller slightly macerated, larger better preserved; antennae about 4 times as long as wide; acicular lobe single, a few parapodia with a short, rounded, basal lobe but most with a tapered, blunt acicular lobe].

Northwestern Africa. 1 specimen, BMNH 1955.8.22.9, Canary Islands, Arrecife , spring 1955, C. Totton coll. [43 mm long, 5 mm wide; prostomium as long as wide; antennae digitate, 4-5 times as long as wide; anterior eyes slightly larger than posterior ones; right parapodium of chaetiger 9 removed for observation (kept in vial); acicular lobe single; neurochaetal blades bidentate, subdistal tooth as wide as distal one, guards approaching subdistal tooth; oocytes 100 µm in diameter].

DISTRIBUTION. — Despite the fact that Fauvel recorded this species for many localities worldwide, its distribution is rather restricted to the Mediterranean region, and adjacent areas in the Eastern Atlantic, in shallow water.

DIAGNOSIS. — Hesione with prostomium rectangular; parapodia with dorsal cirri basally cylindrical, dorsal cirrophore twice as long as wide; larger acicula blackish; acicular lobe single, short or long, digitate or slightly swollen distally, lower tine missing; neurochaetal blades bidentate, 6-7 times as long as wide; subdistal tooth smaller than distal one, with guards approaching distal tooth.

DESCRIPTION

Neotype, MNHN-IA-TYPE1850 (formerly jar 70-190b), complete, tapered, colorless ( Fig. 35A ) in ethanol, integument dorsally smooth, variably corrugated; posterior end smashed, bent laterally, several tentacular and dorsal cirri lost; neurochaetal lobes contracted; right parapodium from chaetiger 9 removed and dissected for acicular features (kept in container); body 37 mm long, 5 mm wide.

Prostomium rectangular, slightly as wide as long ( Fig. 35B ), anterior margin projected, posterior margin with a shallow, short furrow, about as long as 1/5 prostomial length; longitudinal depression very shallow. Antennae minute, digitate, tapered, directed laterally, as long as anterior eyes cornea, or 3-4 times as long as wide. Eyes without pigmentation, corneas distinct, anterior ones larger, placed about the median region, more distant to each other than posterior ones.

Tentacular cirri without tips, reaching anterior margin of pharynx, or back to chaetiger 4. Lateral cushions barely projected, separated into two sections in anterior and medial regions, three posteriorly.

Parapodia with dorsal cirri mostly without tips ( Fig. 35C ); cirrophore annulated, twice as long as wide; cirrostlyle cylindrical, smooth basally, articulated medially and distally. Neuropodia thick, tapered, blunt, annulated basally. Ventral cirri with cirrophore small, almost indistinct; cirrostyle longer than chaetal lobe.

Neuraciculae black, tapered, distally swollen, some mucronate. Acicular lobes single, digitate, blunt ( Fig. 35C [inset]), markedly projected in specimen MNHN-IA-TYPE1850 ( Fig. 36A, B [insets]).

Neurochaetae about 20 per bundle ( Fig. 35D ), blades bidentate, 6-7 times as long as wide, slightly shorter ventrally, with a smaller subdistal tooth, guard approaching or barely surpassing subdistal tooth ( Fig. 35D [insets]).

Posterior end tapered into a blunt cone ( Fig. 35E ), directed ventrally; pygidium with all cirri on site, anus exposed with about 6 low papillae.

Pharynx fully exposed, 5 mm long, made by two rings, distal one ¼ as long as whole pharynx, basal ring longer; dorsal papilla 1.5 times as long as wide, tip rounded. Oocytes not seen.

REMARKS

Hesione pantherina Risso, 1826 has been confused for several reasons (see below), and it has been regarded as a cosmopolitan species; in order to clarify its taxonomic status ( ICZN 1999: art. 75.3.1), a neotype is proposed to define and restrict it. The neotype has been described above and the differences to other species are listed below ( ICZN 1999: art. 75.3.2, 75.3.3). There were no type specimens deposited nor present in the Paris museum ( ICZN 1999: art. 75.3.4), and the neotype and additional specimens share the same diagnostic features ( ICZN 1999: art. 75.3.5). The neotype was collected in the same region, off Nice ( ICZN 1999: art. 75.3.6), and it is now deposited in the Paris museum ( ICZN 1999: art. 75.3.7).

In the original description of Hesione pantherina, Risso (1826) confused body ends and this explains why there is a discordance between the number of cirri indicated for each body end, against the number that are usually present. This confusion was noted by Audouin & Milne-Edwards (1833: 234, footnote 1). Further, Risso described the pigmentation pattern including transverse lemon-yellow bands, but these bands have not been confirmed, although paler transverse bands can be present in some specimens.

Perhaps the best account of H. pantherina was made by Fauvel (1923a: 233); however, there are some differences between his illustrations and the observed features in the Mediterranean specimens. The main differences are: 1) the anterior prostomial margin is not incurved as illustrated if specimens have their pharynx invaginated, but appears anteriorly projected; 2) antennae are as long as interocular distance, not shorter as indicated in his illustrations; and 3) ventral cirri are markedly longer than chaetal lobes, not slightly longer as depicted in the illustrations. Neurochaetal blades, however, were well illustrated with their guards reaching subdistal tooth. These discrepancies imply Fauvel grouped different species under the same name, and this is evident from the pigmentation pattern; he indicated: “coloration assez variable, moucheté de brun et réticulé de blanc, ou tigré de taches brunes allongés ou arrondies.” (Transl.: pigmentation very variable, spotted with brown and reticulated white, or striped with longitudinal or round brownish spots).

As shown in the key below, H. pantherina resembles H. panamena Chamberlin, 1919 , reinstated. Their main difference is the type of acicular lobe because in H. pantherina they can be short or long but their tips are blunt to distally swollen, whereas in H. panamena acicular lobes are long, tapered. Another difference is in pigmentation of living specimens: in H. pantherina there are middorsal pale areas, whereas in H. panamena there are middorsal blackish, round spots.

Besides H. pantherina , there are two other species described from the Northeastern Atlantic and Mediterranean: H. sicula delle Chiaje, 1830 and H. steenstrupi de Quatrefages, 1866 . It must be emphasised that parapodial features, especially the type of acicular lobes, were not included for the original description of any of these three species. Saint-Joseph (1898) made a detailed illustration of parapodial and chaetal features and, quite surprisingly, he even illustrated acicular tips. Thus, his plate 19 shows that antennae are shorter than interocular distance (1898: fig. 131), acicular lobes are double and blunt (1898: fig. 135), neuraciculae are slightly capitate with distal tiny spines (1898: fig. 137), and chaetal blades are bidentate with subdistal tooth larger than distal tooth and guard approaches subdistal tooth (1898: fig. 136). As indicated below, these features match H. steenstrupi and his material was collected in Saint-Jean-de-Luz, close to the type locality (Guethary), in the Gulf of Vizcaya.

Saint-Joseph (1898) also compared his material against specimens from Naples, close to the type locality of H. sicula , and concluded that they were identical with his materials, leading him to conclude that the three species ( H. pantherina , H. sicula , H. steenstrupi ) were synonyms and the senior synonym should be H. pantherina . It must be emphasised that H. sicula and H. steenstrupi share the presence of acicular lobes double, and some other differences are needed to retain both specific names, but none has been found (see below).

On the other hand, as indicated above, H. pantherina has acicular lobes single, and this difference is enough to keep it separate from the two other species. Fauvel (1923a: 234) followed Saint-Joseph about the synonymy, and when referring to acicular lobes, he indicated that “au-dessus des soies une ou deux petites languettes coniques, souvent rétractées” (Transl.: over the chaetae there is one or two small conical lobes, often retracted). Fauvel was actually reiterating something he had concluded before ( Fauvel 1911: 375), when he recorded H. pantherina for the Persian Gulf, and rejected the use of acicular lobes as diagnostic features: “j’observe à cet égard une grande variabilité, non seulement d’un individu à l’autre mais encore d’un parapode à l’autre sur un même animal.” (Transl.: I observe about this (acicular lobes) a large variability, not only from one specimen to the other but even from one parapodium to another one in the same specimen). This is incorrect. After a comparison of the corresponding illustrations ( Fauvel 1911: 375, fig. IV), it is clear that parapodia were mounted differently, as indicated by the relative position of the ventral cirri, such that if these parapodia came from the same specimen they were probably drawn from different perspectives, or worse, they belong to different specimens.

Pleijel (1998: 159) indicated that “ H. sicula delle Chiaje, 1822” could be a junior synonym of Hesione pantherina Risso, 1826 . If they are really the same species, the senior synonym should be H. sicula ; the contrary perspective rejects the principle of priority ( ICZN 1999: art. 23), but as indicated below, the type of acicular lobe separates these two species. Further, the correct publication date for H. sicula is 1830, as part of a series of plates, as indicated below.

The record by McIntosh (1885: 185, 186, pl. 29, fig. 1, pl. 32, fig. 16, pl. 15A, fig. 10) as Hesione (Fallacia) pantherina for the Cape Verde islands could not be resolved because the specimen is dried out (BMNH 1885.12.1.137), and the original illustrations do not depict the acicular lobe.

Figures

FIG. 35. — Hesione pantherina Risso, 1826, neotype, MNHN-IA-TYPE1850 (formerly jar 70.190b): A, anterior region, dorsal view; B, prostomium and basal ring of pharynx; C, chaetiger 9, right parapodium, anterior view (inset: acicular lobe); D, same, neurochaetae (insets: blades); E, posterior region, dorsal view. Scale bars: A, 1 mm; B, 0.4 mm; C, 1.7 mm; D, 75 µm; E, 1.5 mm.

FIG. 36. — Hesione pantherina Risso, 1826, specimen MNHN-IA-TYPE1851 (formerly jar 70.190c): A, chaetiger 4, right parapodium, anterior view (inset: acicular lobe); B, chaetiger 7, left parapodium, anterior view. Scale bars: A, 0.6 mm; B, 0.3 mm.