Diplomma, STIMPSON, 1857

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 : 699-700

GENUS DIPLOMMA STIMPSON, 1857

Diplomma Stimpson, 1857: 164 (type species: Nareda serpentina Stimpson, 1855 , fixed by monotypy).

Paramphiporus Kirsteuer, 1965: 294 (type species: Paramphiporus albimarginatus Kirsteuer, 1965 , fixed by monotypy), syn. nov.

Diagnosis: Distromatonemerteans with mid-dorsal blood vessel running always under rhynchocoel; dorsoventral muscles occasionally passing laterally to (= outside) lateral nerve cords; body colour uniformly brownish in life.

Composition: The following four species are here regarded as congeners: Diplomma albimarginata ( Kirsteuer, 1965) comb. nov., Diplomma bothwellae ( Gibson, 1982) comb. nov., Diplomma polyophthalma ( Gibson & Sundberg, 2001) comb. nov., and Diplomma serpentina ( Stimpson, 1855) .

Remarks: In addition to the diagnostic characters, the following features are found in both in D. serpentina and D. polyophthalma comb. nov., thus may be used as a guide in identifying species in the genus: (1) single neuropil in lateral nerve cord; (2) short intestinal caecum, not reaching to brain, having neither anterior nor lateral pouches; (3) eyes that tend to be difficult to observe in life; (4) rhynchocoel being almost full body length; (5) single shallow apical organ (not elaborated as those in prosorhochmids); (6) cephalic gland restricted precerebrally; and (7) postcerebral submuscular glands absent.

Congeners have so far been known from the temperate to tropical Western and Central Indo-Pacific. Possible additional congeners, which are at present classified in other genera, include Amphiporus insolitus Iwata, 1954a described from Japan and Amphiporus texanus Coe, 1951a sensu Corrêa (1961) reported from Virginia Key, Miami ( USA). Morphologically, congeners can be discriminated by the number of proboscis nerves (indicated in parentheses): D. albimarginata comb. nov. (15), D. bothwellae comb. nov. (10), D. polyophthalma comb. nov. (13–14), and D. serpentina (12).