Prosadenoporus spectaculum ( Yamaoka, 1940 ) Maslakova & Norenburg, 2008

Maslakova, Svetlana A. & Norenburg, Jon L., 2008, Revision of the smiling worms, genera Prosadenoporus Bürger, 1890 and Pantinonemertes Moore and Gibson, 1981 and description of a new species Prosadenoporus floridensis sp. nov. (Prosorhochmidae; Hoplonemertea; Nemertea) from Florida and Belize, Journal of Natural History 42 (25 - 26), pp. 1689-1727 : 1718-1720

Prosadenoporus spectaculum ( Yamaoka, 1940) , new combination

( Figures 9 C–I; Table 3)

Prostoma spectaculum ( Yamaoka 1940) .

Pantinonemertes spectaculum ( Gibson 1990; Gibson and Sundberg 1992; Sun 2001).

Etymology

The name reflects the unique spectacle-shaped pattern of pigmentation on the head of this species.

Type material

Type material almost certainly lost.

Material examined

Prosadenoporus spectaculum ( Yamaoka, 1940) comb. nov. Two sectioned specimens 1987-2-43 and 1987-2-42 held at the Museum of Natural History, London, UK.

Diagnosis

Prosadenoporus spectaculum comb. nov. is distinguished from other species in the genus by the characteristic spectacle or helmet-shaped pattern of pigmentation on the head. Additionally, P. spectaculum differs from P. winsori in lacking neurochords and from both P. winsori and P. fujianensis by having a single pair of accessory stylet pouches. It differs from P. mooreae , P. mortoni , P. enalios and P. arenarius by having neurochord cells ( Figure 9G ) and from P. agricola and P. floridensis by having more proboscis nerves (18–22 compared with 11–14 in P. floridensis and 12–15 in P. agricola ). The shape and size of stylet and basis are not known.

Habitat and distribution

Originally described from Naha and Tinen, Riukiu Islands, Japan; habitat unknown. Three specimens on which the re-description by Gibson (1990) is based were collected from rock crevices and clefts just below high tide level in Starfish Bay and Tai Mong Tsai, Hong Kong.

Remarks

Gibson (1990) stated that one of the diagnostic features of this species is presence of the split precerebral septum ( Kirsteuer 1974). Our re-investigation of one of the Hong Kong specimens deposited at the British Museum of Natural History revealed that the structure of the precerebral septum (i.e. proboscis insertion muscles) in this species is the same as in other members of the genus; that is there is no distinct precerebral septum. However, we observed that the voucher specimen is severely contracted – as evident from the position of lateral nerve cords – which causes longitudinal muscle fibres in the proboscis insertion to appear as radial, giving the impression of the ‘‘split precerebral septum’’ ( Figures 9H and 9I ).

Prosadenoporus winsori ( Moore and Gibson, 1981) , new combination ( Figures 1B, 1E, 1F , 7 J–L, 8A–E, 10G and 10H; Tables 1–4) Pantinonemertes winsori ( Moore and Gibson 1981) .

Etymology

The species is named after Dr Leigh Winsor, who first drew attention to the species.

Type material

Prosadenoporus winsori ( Moore and Gibson 1981) comb. nov. Sections of the holotype W5895 and paratype W5896 are deposited at the Australian Museum, Sydney, Australia.

Material examined

Prosadenoporus winsori ( Moore and Gibson, 1981) comb. nov. Holotype W5895, paratype W5896. Additional sectioned specimen deposited at the Museum of Natural History in London 1978-12-2 (coll. R. Gibson , Townsville , Queensland, Australia) and five specimens collected by SAM in March 2003 from the type locality near Townsville , Queensland, Australia, four of which are partly sectioned and held at the National Museum of Natural History in Washington, DC, USA ( USNM1087362–1087364 , 1087366 ). The unsectioned specimen in 70% ethanol deposited at the Museum of Tropical Queensland, Townsville, Queensland, Australia (G20043).

Diagnosis

Prosadenoporus winsori comb. nov. is the only species in the genus to possess neurochords ( Figure 7J ). It differs from all other species of the genus except P. fujianensis in having multiple accessory stylet pouches. It additionally differs from P. fujianensis by the presence of a pale midline stripe on the dorsal surface of living specimens and by having 22–24 proboscis nerves (compared with 19–20) and more accessory stylet pouches (6–9 compared with 5–6). Central stylet5200– 360 mm long, average 5233.3 mm, basis (B) truncated, 490–850 mm long, average 5686.7 mm, S:B ratio50.25–0.5, average50.34. All three stylet metrics are significantly different from those of P. floridensis and P. mooreae (p 50.05). Data at hand are insufficient to make statistical comparisons with other species. Average sequence divergence between P. winsori and other sequenced Prosadenoporus species is 8.7% and 10.5% for 16S and COI respectively ( Tables 1 and 4).

Habitat and distribution

Semi-terrestrial or upper intertidal. Beneath bark or in cavities and burrows of teredinid bivalves in rotting fallen mangrove timber ( Avicennia marina (Forsk.) , Ceriops tagal (Perr.)) ; associated with polychaetes, teredinid bivalves, crustaceans (especially the grapsid decapod Sesarma erythrodactyla Hess ), polyclad flatworms, coleopteran larvae and ants. In estuaries of Ross River (south bank) and Three Mile Creek, near Townsville, Queensland, Australia.

Remarks

Number of accessory stylet pouches is not mentioned in the original description ( Moore and Gibson 1981). We investigated stylet armature in four out of five specimens collected by SAM from the type locality in March 2003 – two had six, one had seven and one had nine accessory stylet pouches .

Figures

Figure 1. External appearance of members of Prosadenoporus. (A) Female and male of Prosadenoporus floridensis sp. nov.; (B) Prosadenoporus winsori comb. nov. on a piece of rotten mangrove penetrated by teredinid burrows (its natural habitat); (C–D) Prosadenoporus mooreae comb. nov.; (E–F) anterior end of P. winsori (E5lateral view; F5dorsal view). Notes: cg, cerebral ganglia; pf, posterior cephalic furrow; sm, prosorhochmid smile. Scales: (A and C), 3 mm; (B), 20 mm; (D), 0.5 mm; (E and F), 1 mm.

Figure 7. Microscopic anatomy of Prosadenoporus species.(A–C) A series of transverse sections through the frontal organ of Prosadenoporus enalios comb. nov.; relative position of the lateral acidophilic regions (arrowheads) indicate a noticeable twist of the frontal organ canal; (D) a longitudinal sagittal section through frontal organ of Prosadenoporus mooreae comb. nov. (anterior to the right); (E–I) a series of slightly oblique transverse sections through the frontal organ of P. mooreae comb. nov.; lateral acidophilic regions of the frontal organ (arrowheads), note the twisting of the frontal organ canal; (J) transverse section through lateral nerve cord of Prosadenoporus winsori comb. nov. showing the tentative neurochord (arrowhead); (K) binucleate terminal cells of nephridia (flame cells) of P. winsori comb. nov. (arrowheads); (L) a longitudinal sagittal section through the frontal organ of P. winsori comb. nov. (anterior to the left). Notes: bgl, basophilic cephalic glands; cg, cerebral ganglia; fo, frontal organ; lnc, lateral nerve cord; rhd, rhynchodeum. Scales: (A–C), and (E–I), 50 mm; (D), 100 mm; (J), 30mm; (K), 20mm; (L), 200mm.

Figure 9. (A–B) Transverse sections through the frontal organ of Pantinonemertes californiensis; (C–I) Prosadenoporus spectaculum comb. nov.: (C–F) a series of transverse sections through the tip of the head showing frontal organ twisting; lateral acidophilic regions of the frontal organ marked with arrowheads; (G) transverse section through the cerebral ganglia showing two neurochord cells (circled, insert); (H) transverse section through the proboscis insertion and anterior portion of cerebral ganglia showing contracted proboscis insertion muscles; (I) transverse section through the posterior region of brain showing beginning of the lateral nerve cords (asterisks) which appear sectioned longitudinally, presumably because of the severe contraction of the specimen during fixation. Notes: bgl, basophilic cephalic glands; cg, cerebral ganglia; fo, frontal organ; ogl, orange-G cephalic glands; vc, ventral brain commissure. Scales: (A–F), 50 mm; (G), 100 mm (insert, 50mm); (H–I), 200 mm.