Prosorhochmus claparedii Keferstein, 1862

Maslakova, Svetlana A. & Norenburg, Jon L., 2008, Revision of the smiling worms, genus Prosorhochmus Keferstein, 1862, and description of a new species, Prosorhochmus belizeanus sp. nov. (Prosorhochmidae, Hoplonemertea, Nemertea) from Florida and Belize, Journal of Natural History 42 (17 - 18), pp. 1219-1260 : 1246-1247

Prosorhochmus claparedii Keferstein, 1862

( Figures 1E , 7E , 8G–L , 9B ; Tables 1–4)

Planaria flava ( Montagu 1808)

Polia fumosa ( Quatrefages 1846; 1849)

Nemertes fumosa ( Diesing 1850)

Tetrastemma fumosum ( Diesing 1863)

Prosorhochmus claparédii ( Keferstein 1862; Diesing 1863; McIntosh 1869; Bürger 1904; Campbell 1982)

Prosorochmus claparédii ( Claparéde 1863)

Prosorhochmus claparedii ( McIntosh 1873 –1874; Dewoletzky 1880, 1887; Chapius 1886; Sheldon 1896; Bürger 1897 –1907; Gontcharoff 1955; Pantin 1969; Gibson 1972, 1982a, 1982b; Friedrich 1979; Anadón 1980; Gibson and Moore 1985; Gibson et al. 1986; Senz 1993; Frutos et al. 1998; Maslakova et al. 2005)

Prosorochmus claparedii ( Czerniavsky 1880; Joubin 1890; Oxner 1907b) Phrosorochmus claparedii ( Joubin 1889) , [ Lapsus calami ]

Prosorochmus claparedii

Prosorochmus claparedei ( Joubin 1894) , [ Lapsus calami ]

Prosorhochmus claparèdi ( Bürger 1895, 1897 –1907; Friedrich 1936; Campbell 1976), [ Lapsus calami ]

Prosorhochmus claparedi ( Friedrich 1955; Marine Biological Association 1957; Bruce et al. 1963), [ Lapsus calami ]

Prosorhochmus claparedei ( Pantin 1961) , [ Lapsus calami ]

Etymology

The species is named after Professor Jean Louis René Antoine Édouard Claparède, a Belgian zoologist, who originally drew attention to the species and provided illustrations of live specimens.

Type material

Type material was never designated and the original specimens are almost certainly lost.

Material examined

Prosorhochmus claparedii Keferstein, 1862 . CMZ # A6, # A7, # CH 1, ‘‘Ray J’’, ‘‘Ray’’. Coll. R. Gibson, Anglesey, England. Additional material: USNM 1020508, 1020509. Coll. SAM, Bilbao, Spain; USNM 1020510-1020513. Coll. SAM. Roscoff, France.

Diagnosis

Prosorhochmus claparedii does not possess any known morphological apomorphies. It differs from Prosorhochmus nelsoni ( Sanchez, 1973) and Prosorhochmus belizeanus sp. nov. in being viviparous and hermaphroditic ( Figure 1E ) and additionally from P. belizeanus sp. nov. in having acidophilic cephalic glands intermixed with the basophilic mucus cephalic glands in the pre-cerebral and cerebral region ( Figure 9B ). It differs from Prosorhochmus americanus in lacking well-developed purple cephalic glands and in having but a single juvenile per ovary. Prosorhochmus claparedii closely resembles P. chafarinensis , however, they can be differentiated by stylets (although the data at hand do not show them to be statistically significantly different) (see Tables 2, 3) and sequence data ( Table 4). Central stylet (S) 30–95 Mm long, statistically different from that of P. belizeanus sp. nov. but not P. chafarinensis or P. nelsoni (p50.05), basis (B) truncated, 90–165 Mm long, statistically different from that of P. belizeanus sp. nov. but not P. chafarinensis or P. nelsoni (p50.05); S/B ratio 0.25–0.62, statistically different from that of P. nelsoni but not P. belizeanus sp. nov. or P. chafarinensis (p50.05), (see Tables 2, 3). At present P. claparedii cannot be distinguished from the insufficiently described Prosorhochmus adriaticus Senz, 1993 .

Habitat and distribution

Typically found beneath stones and boulders on coarse sand or in rock fissures in the mid- to upper-shore zones, but can also be obtained by sublittoral dredging. In the Plymouth district of England it extends to crevices at the top of the Pelvetia belt, where it co-occurs with collembolans, myriapods, chernetids and gastropods transitional to land forms ( Pantin 1969). Gregarious, with several specimens often found together under the same rock. Wembury and the Yealm, Plymouth; Trwyn Du Point, Anglesey ( Gibson and Moore 1985); Port Sr. Mary in the Isle of Man ( Bruce et al. 1963), Port Trefadog, Anglesey ( Eason 1973); the southern shores of England and St. Peter Port, Guernsay ( McIntosh 1873 –1874) around the British Isles; from north of Tisaoson (ty-Zaoson) near Roscoff, Finistère ( Chapius 1886; Gontcharoff 1955), Roscoff ( Joubin 1890; SAM), Île Bréhat, Côtes-du-Nord ( Quatrefages 1846), St. Vaast-la-Hougue, Manche ( Quatrefages 1846; Keferstein 1862) and Le Portel, Pas-de-Calais ( Joubin 1894) on the northern coast of France; San Esteban de Pravia, Asturias, ( Anadón 1980) and in the vicinity of Bilbao, northern Spain (SAM). Near Trieste in the Adriatic Sea ( Dewoletzky 1880), Naples in the Mediterranean ( Bürger 1895); possibly Black Sea ( Bürger 1895, Bürger 1904).

Remarks

We compared sections of the material on which Gibson and Moore (1985) based their redescription of the species and those of specimens collected by SAM from Bilbao, Spain and Roscoff, France and found them to be morphologically indistinguishable. However, we noted that the higher degree of development of the frontal organ reported by Gibson and Moore (1985, p. 153) for P. claparedii is apparently a result of misinterpreting a slightly oblique cross-section as a vertical longitudinal (i.e. sagittal) section of the frontal end ( Gibson and Moore 1985, p. 149, plate I, fig. e). Our reinvestigation shows that the frontal organ of this species is similar in structure and shape to that of the other species of Prosorhochmus (see Figures 4C–D , 5A–C, 5G–H , 8A–J , 9D–F ). Furthermore, after re-investigating all of the available material, we cannot confirm the reported presence of distinct nerves in the posterior proboscis chamber of this species ( Gibson and Moore 1985, p. 151), transverse blood vessel connectives ( Gibson and Moore 1985, p. 153) and the presence of the neurochord cells ( Gibson and Moore 1985, p. 153). Originally defined by Bürger (1895, p. 355), neurochord cells represent a single pair of giant neurons located in the inner portion of the ventral cerebral ganglia in the vicinity of the ventral commissure. Other large cells in the cerebral ganglia – most likely the type III neurons as defined by Bürger (1895, p. 320), have apparently been mistaken for neurochord cells by Gibson and Moore (1985). Stylet measurements of three specimens collected by SAM in Roscoff, France (close to the type locality) are as follows: central stylet (S) 80–95 Mm long, basis (B) 130–165 Mm long; S/B ratio ranging from 0.58 to 0.62 (0.60 on average). These are larger than the measurements reported by Gibson and Moore (1985) (see Table 2). However, because only ranges of variation are available and the number of specimens and average values are not known, it is not possible to determine whether this difference is statistically significant. Because of the geographical proximity of our collecting sites to the type locality and England (where Gibson and Moore’s specimens came from) and the fact that our specimens are otherwise indistinguishable from the English P. claparedii , we assume that our specimens belong to the same species and that if more specimens were available the difference in stylet measurements would turn out to be insignificant. This is why we pool the measurements to adjust the ranges of variation in species diagnosis.

Figures

Figure 1. External appearance and habitat of Prosorhochmus species. (A) Typical intertidal habitat of Prosorhochmus spp. – wet coarse sand just above the low tide mark with partially embedded rocks. The pictured location is about halfway between Croatian towns Savudrija and Zambratija on the Adriatic coast; (B–C) Prosorhochmus chafarinensis, anterior end (B, dorsal view; C, ventral view); (D) Arhochmus korotneffi comb. nov., anterior end, dorsal view; (E) Prosorhochmus claparedii, external appearance of a viviparous hermaphroditic adult with several juveniles showing through the body wall between the gut diverticula; (F) P. chafarinensis, external appearance of viviparous hermaphroditic adult with two newly born juveniles; (G) A. korotneffi, external appearance of a viviparous hermaphroditic adult with several juveniles showing through the body wall; (H) Prosorhochmus belizeanus sp. nov. external appearance of sexually mature male (left) and female (right). Testes show through the body wall as whitish sacks regularly interspersed with gut diverticula on either side. Pinkish oocytes in ovaries are visible through the body wall of ripe females. Scales. (B–D): 0.5 mm; (E): 3mm; (F, G): 6 mm; (H): 3.5 mm. Abbreviations: cof, cerebral organ furrow; j, juvenile; sm, prosorhochmid smile.

Figure 4. Prosorhochmus belizeanus sp. nov. (A) Transverse section through the body wall; (B) longitudinal section through the body wall showing diagonal muscles; (C, D) longitudinal sagittal sections through the precerebral and cerebral region showing frontal organ (arrowhead), precerebral septum and acidophilic cephalic glands; anterior is to the right; (E) transverse section showing well-developed dorso-ventral muscles in the midgut region; (F) transverse sections through the stomach showing the ventral stomach pouch and welldeveloped dorso-ventral muscles; (G) transverse section through precerebral region showing numerous muscle fibres oriented in all possible directions, rhynchodeum (asterisk) and an ocellus (arrowhead); (H) transverse section through the anterior oesophageal region showing foregut or ‘‘splanchnic’’ muscles; (I) transverse section through the sparsely ciliated posterior oesophagus; (J) transverse section through the deeply folded stomach showing ‘‘splanchnic’’ muscles (arrows); (K) transverse section through the anterior rhynchodeum; (L) transverse section through the rhynchodeum just in front of the proboscis insertion. Scales. (A, B, E, F, H–L): 50 Mm; (C, D, G): 100 Mm. Abbreviations: agl, acidophilic cephalic glands; bgl, basophilic cephalic glands; cae, caecum; cg, cerebral ganglia; cm, circular muscles; dvm, dorsoventral muscles; ep, epidermis; es, oesophagus; int, intestine; lm, longitudinal muscles; ogl, orange-G cephalic glands; pb, proboscis; ps, precerebral septum; rhd, rhynchodeum; spm, foregut or ‘‘splanchnic’’ muscles; stm, stomach; stp, stomach pouch; ts, testis.

Figure 5. Prosorhochmus belizeanus sp. nov. (A–C) A series of transverse sections through the frontal organ from anterior to posterior; lateral acidophilic regions marked by arrowheads. (D) Transverse section through the cerebral organ furrow and posterior ocellus. (E) Transverse section through the cerebral organ (outlined). (F) Transverse section through the intestinal region of a mature male. (G, H) Slightly oblique transverse sections through the tip of the head: prosorhochmid smile (G) and frontal organ (H). Scales on (A–E) - 50 Mm; on (G, H) - 100 Mm; on (F) - 200 Mm. Abbreviations: agl - acidophilic cephalic glands, bgl - basophilic cephalic glands, co - cerebral organ, cof - cerebral organ furrow, fo - frontal organ, int - intestine, pb - proboscis, pc - pigment cup of ocellus, rhd - rhynchodeum, ts - testis.

Figure 7. Central stylets. The 100 Mm scale bar applicable to all, except (I). (A, B) Prosorhochmus chafarinensis (specimens from Croatia); (C, D) Arhochmus korotneffi comb. nov. (specimens from Croatia); (E) Prosorhochmus claparedii (specimen from Roscoff, France); (F) P. chafarinensis (after Frutos et al., p. 294, fig.1b); (G) Prosorhochmus americanus (after Gibson et al. 1986, p. 330, plate I, fig. e); (H) Prosorhochmus nelsoni (specimen from Coquimbo, Chile); (I) Prosorhochmus belizeanus sp. nov (200 Mm scale bar).

Figure 8. (A) Slightly oblique transverse section through frontal organ of Arhochmus korotneffi comb. nov.; (B) longitudinal sagittal section through frontal organ of A. korotneffi; anterior to the left; (C) longitudinal sagittal section through frontal organ of Prosorhochmus americanus; anterior to the left; (D–F) a series of transverse sections through the frontal organ of P. americanus from anterior to posterior showing lateral acidophilic regions of frontal organ (arrowheads); (G–I) a series of transverse sections through the frontal organ of Prosorhochmus claparedii showing lateral acidophilic regions of frontal organ (arrowheads); (J) longitudinal sagittal section through frontal organ of P. claparedii; anterior to the left; (K–L) transverse sections through stomach (K) and pylorus (L) of P. claparedii showing welldeveloped dorso-ventral muscles (arrowheads). Scales (A–F, J–L): 50 Mm; (G–I): 25 Mm. Abbreviations: bgl, basophilic cephalic glands; cae, caecum; cdiv, caecal diverticulum; fo, frontal organ; lnc, lateral nerve cord; pb, proboscis; pyl, pylorus; rhst, rhynchostome; stm, stomach.

Figure 9. (A–C) Transverse sections through the precerebral region at the level of cerebral organs to show acidophilic, purple and basophilic cephalic glands: Prosorhochmus americanus (A), Prosorhochmus claparedii (B) and Prosorhochmus chafarinensis (C); (D–E) two slightly oblique transverse sections through the frontal organ of P. chafarinensis; (D) anterior opening into prosorhochmid smile; (E) middle portion of the canal; lateral acidophilic regions marked with arrowheads; (F) longitudinal sagittal section through frontal organ of P. chafarinensis. Scales: 50 Mm. Abbreviations: agl, acidophilic cephalic glands; bgl, basophilic cephalic glands; es, oesophagus; fo, frontal organ; pb, proboscis; pgl, purple cephalic glands; rhd, rhynchodeum.