Diplomma bothwellae Kajihara & Olympia & Kobayashi & Katoh & Chen & Strand & Sundberg, 2011

Kajihara, Hiroshi, Olympia, Minerva, Kobayashi, Norio, Katoh, Toru, Chen, Hai-Xia, Strand, Malin & Sundberg, Per, 2011, Systematics and phylogeny of the hoplonemertean genus Diplomma (Nemertea) based on molecular and morphological evidence, Zoological Journal of the Linnean Society 161 (4), pp. 695-722 : 702-703

DIPLOMMA BOTHWELLAE ( GIBSON, 1982) COMB. NOV. ( FIGS 9–11 )

Poseidonemertes bothwellae Gibson, 1982: 270 , figures 1–4.

Material examined: AM W.5890, the holotype of Poseidonemertes bothwellae Gibson, 1982 , 26 slides, serial transverse sections prepared by Ray Gibson ; obtained from a chunk of coral covered with small algae and hydroids, at an inner reef flat on western Heron Island , Capricorn Group , Great Barrier Reef, Australia, by Anne Bothwell on 15.vii.1975 .

For comparison, AMNH 278, the holotype of Poseidonemertes gondwanae Kirsteuer, 1967b (type species of the genus Poseidonemertes ) and AMNH 279, the holotype of Poseidonemertes caribensis Kirsteuer, 1974 were also examined.

Distribution: Great Barrier Reef, Australia (only known from the type locality).

Diagnosis: Diplomma with proboscis having ten nerves ( Fig. 9 ); eyes four in number.

Supplementary redescription: Dorsoventral muscle fibres running laterally to the lateral nerve cords are found on almost every section from the stomach region through the pyloric region ( Figs 10 , 11 ), as if they form a ‘body-wall inner circular muscle layer’. These fibres become sparse posteriorly, although they are still sporadically found in the intestinal region. The intestinal caecum extends for 35 slices, equivalent to 210–245 Mm long.

Note on Poseidonemertes: Contrary to the descriptions of Poseidonemertes gondwanae given by Kirsteuer (1967b, 1974), our observation of the holotype revealed that the mid-dorsal blood vessel enters the rhynchocoel for a very short course soon after its origin ( Fig. 12 ) and the diagonal muscle layer is well developed ( Fig. 13A ); additionally, dorsoventral muscle fibres always run medial to the lateral nerve cord ( Fig. 13B ), a character state not mentioned by Kirsteuer (1967b, 1974). We also confirmed the presence of a thin thread of nerve covered by connective tissues, horizontally sent from the lateral nerve cord to the epidermis on each side ( Fig. 13B ) in the foregut and intestinal regions. This character has been reported at least in Poseidonemertes collaris by Roe & Wickham (1984) and in Poseidonemertes buergeri by Senz (2001); this might be used in diagnosing the genus Poseidonemertes or distinguishing congeners.

DIPLOMMA POLYOPHTHALMA ( GIBSON &

Figures

Figure 9. Diplomma bothwellae comb. nov. (formerly Poseidonemertes bothwellae Gibson, 1982). Holotype (AM W.5890). Transverse section through the anterior proboscis; arrows indicate the proboscis nerves. Scale bar = 20 Mm.

Figure 10. Diplomma bothwellae comb. nov. (formerly Poseidonemertes bothwellae Gibson, 1982). Holotype (AM W.5890). Transverse section through the pylorus (PY) and intestinal caecum (IC); arrows indicate dorsoventral muscle fibres running lateral to the lateral nerve cord (LN). Scale bar = 100 Mm.

Figure 11. Diplomma bothwellae comb. nov. (formerly Poseidonemertes bothwellae Gibson, 1982). Holotype (AM W.5890). Magnification of Figure 10 to show the dorsoventral muscle fibres (arrowed). Abbreviations: EP, epithelium; LN, lateral nerve cord; LV, lateral blood vessel; RC, rhynchocoel. Scale bar = 20 Mm.

Figure 12. Poseidonemertes gondwanae Kirsteuer, 1965. Holotype (AMNH 278). A–F, serial transverse section to show that mid-dorsal vessel enters rhynchocoel. Abbreviations: DV, mid-dorsal vessel; LV, lateral blood vessel; RC, rhynchocoel; VP, vascular plug. Scale bar = 50 Mm.

Figure 13. Poseidonemertes gondwanae Kirsteuer, 1965. Holotype (AMNH 278). A, diagonal muscle layer between body-wall outer circular and inner longitudinal muscle layers. B, horizontal nervous thread from lateral nerve cord to the epidermis (indicated by white arrows); black arrows indicate dorsoventral muscle fibres running inside lateral nerve cord. Abbreviations: CM, body-wall circular muscle layer; DE, dermis; DM, diagonal muscle layer; IN, intestine; LN, lateral nerve cord; RC, rhynchocoel. Scale bars: A = 30 Mm; B = 50 Mm.