Prostoma padanum, Pierantoni, 1926

Kajihara, Hiroshi, 2025, A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping?, Zootaxa 5646 (4), pp. 451-500 : 470

19. padanum Pierantoni, 1926

Source. Pierantoni (1926: 436) noted “ Prostoma padanum ” and “ P. padanum sp. nov. ”, but in a taxonomic heading on another page “ Prostoma (Stichostemma) padanus ” [sic] ( Pierantoni 1926: 440).

Type locality. A slow water flow near the west bank of the River Po in the district Millefonti, Turin, Italy ( Fig. 9 ) .

Etymology. Adjective, padanus , - a, - um, from Padus (the River Po) and the suffix - ānUs, meaning “of the River Po”.

Remarks. Pierantoni (1926) characterized P. padanum as small in size (8 mm long, 0.5 mm wide), with a head tapering anteriorly, almost conical, and a reddish flesh colour near the cephalic region; lacking tactile bristles on both ends of the body; possessing a frontal organ; with the rhynchodaeum opening together with the oesophagus; the rhynchocoel extending posteriorly for 2/3 of the body length; the proboscis anterior chamber the same width as posterior chamber, and twice as long as the latter; and being simultaneous hermaphrodite, with external and probably cross fertilization. Prostoma padanum was regarded as a valid taxon by Stiasny-Wijnhoff (1938: 227), but as a nomen dubium by Gibson & Moore (1976: 194). It was listed as an invalid name by Gibson (1995: 497), but herein considered synonymous with P. clepsinoides .

Figures

FIGURE 9. World map showing distribution of 25 nominal species of freshwater monostiliferous hoplonemerteans indicated by boxes and respective species-group names (three subterranean species are indicated with ‘S’ in parentheses); circles, diamond, and triangles indicate localities of DNA-barcoded individuals; circles, Haplogroup 1 from the UK, Sweden (SE), Italy (IT), Macedonia (MK), Japan (JP), New Zealand (NZ), Mexico (MX), Indiana (IN), and Massachusetts (MA); diamond, Haplogroup 2 from Norway (NO); triangles, Haplogroup 3 from Sweden (SE) and California (CA).