Diplomma albimarginata, (KIRSTEUER, 1965), 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 : 700

DIPLOMMA ALBIMARGINATA ( KIRSTEUER, 1965) COMB. NOV. ( FIGS 5–8 )

Paramphiporus albimarginatus Kirsteuer, 1965: 296 , figures 4, 5, 12A.

Paramphiporus albomarginatus [lapsus calami]: Kirsteuer, 1974: 164.

Material examined: AMNH 277, the syntypes of Paramphiporus albimarginatus , four slides, serial transverse sections of two individuals; Tanikely, Madagascar; collected by Ernst Kirsteuer amongst the corals Acropora pharaonis , Acropora corymbosa , and Seriatopora angulata , during the Österreichische Indo-Westpazifik-Expedition 1959/60.

Distribution: Only known from the type locality, Nosy Tanikely (13°29′S, 48°14′E), Madagascar.

Diagnosis: Diplomma with proboscis having 15 nerves ( Fig. 5 ).

Supplementary redescription: Dorsoventral muscles running laterally (= externally) to the lateral nerve cord were found in the syntypes ( Fig. 6 ), conforming to the present diagnosis of the genus Diplomma . The morphology of the intestinal caecum differs between the two syntype specimens, although Kirsteuer (1965) described that it possessed two anterior pouches situated on both sides of the pylorus. In one syntype, these pouches extend for 31 slices of serial sections ( Fig. 7 ) before they merge posteriorly to form an unpaired intestinal caecum below the pylorus, stretching for six slices; i.e. supposing the serial sections were cut at 10 Mm thick, the intestinal caecum would be 60 Mm long, with two pouches extending for 310 Mm from its anterior end. The sections that contain the pair of anterior pouches show an exceedingly expanded rhynchocoel ( Fig. 7 ), suggesting strong contraction during fixation; the intestinal caecum was thus probably deformed in this specimen. In the other syntype, the anterior end of the intestinal caecum appears on one side of the pylorus ( Fig. 8A ) for seven slices; the caecum posteriorly abuts the pylorus on its lateral and ventral sides ( Fig. 8B ) for 12 slices before the pylorus opens to the dorsal wall of the intestine ( Fig. 8C ); i.e. the intestinal caecum is 190 Mm long (assuming the sections were cut at 10 Mm thick), without anterior and lateral pouches.

Figures

Figure 5. Diplomma albimarginata comb. nov. (formerly Paramphiporus albimarginatus Kirsteuer, 1965). Syntype (AMNH 277). Transverse section showing the proboscis nerves (arrowed). Scale bar = 50 Mm.

Figure 6. Diplomma albimarginata comb. nov. (formerly Paramphiporus albimarginatus Kirsteuer, 1965). Syntype (AMNH 277). Transverse section showing the dorsoventral muscle fibres running laterally to the lateral nerve cord (arrowed) in the stomach region. Abbreviations: EP, epithelium; EX, excretory collecting tubule; LN, lateral nerve cord; RC, rhynchocoel. Scale bar = 20 Mm.

Figure 7. Diplomma albimarginata comb. nov. (formerly Paramphiporus albimarginatus Kirsteuer, 1965). One of the two syntypes (AMNH 277). Transverse section to show the two anterior ‘pouches’ (AP) situated laterally to the pylorus (PY); note the exceedingly expanded rhynchocoel (RC), compared to the body diameter and the proboscis (PR). Scale bar = 100 Mm.

Figure 8. Diplomma albimarginata comb. nov. (formerly Paramphiporus albimarginatus Kirsteuer, 1965). Syntype (AMNH 277). A, transverse section showing anterior portion of unpaired intestinal caecum (arrowed) situated on one side of the pylorus (PY); B, ten sections posterior to A, showing the intestinal caecum (arrowed) lateral and ventral to the PY; C, seven sections posterior to B, showing the PY opening to the dorsal wall of the intestine. Scale bar = 50 Mm.