Table 2 in Description of a new species of Prostheceraeus Schmarda, 1859 and redescription of a poorly known species, Phrikoceros sagamianus (Kato, 1937) comb. n., with inference of their phylogenetic positions within Pseudocerotoidea (Platyhelminthes: Polycladida: Cotylea)

Table 2. Comparison of the dorsal body colour patterns among Prostheceraeus species.
Body colour patternBackgroundSpeciescolourLongitudinal linesTransversal linesSpots or maculaeMarginal linesDistributionRemarksReferenceP. albocinctus Lang, 1884FawnAbsentAbsentVery dense brown dots covering dorsal surface, becoming almost black towards body edge, even more densely packed on bulge; bluish tinge on body edge; larger white dotsNarrow milky-white margin except for pseudotentacular regionNisida at shallow depth, Gulf of Naples, Italy–Lang (1884)P. anomalus Haswell, 1907Translucent creamUnknownUnknownUnknownUnknownPort Jackson, Sydney, AustraliaCharacterised by having ‘receptacula seminalis’Haswell (1907)P. argus (Quatrefages, 1845) †Dark orange-yellowAbsentAbsentSmall white pearl-like dots distributed over body surface; string of purple dots present at some distance from body edgeAbsentSaint-Malo, FranceMarginal eyespots extending to posterior bodyQuatrefages (1845)P. boucheti Prudhoe, 1989BrownishMedian red band extending posteriorly and much narrower one running anteriorly from large yellow spotAbsentSingle large yellow spot lying in median line at junction of anterior and middle third of bodyThin transparent margin enclosing narrow yellow or greenish-yellow band10–20 and 25 m depth at Mayotte, Comoro Is., northern Mozambique–Prudhoe (1989)P. crisostomum Cuadrado et al., 2021Ivory whiteAbsentAbsentLarge conspicuous black spot in posterior middle end; small black dots distributed over dorsal surfaceAbsentSal Island, Cape Verde–Cuadrado et al. (2021)P. crozieri (Hyman, 1939)Semi-transparent white-beigeAbsentWavy, black lines that are often broken and branching laterally and may end in black blotch or orange irregular patchWhite spots regularly or irregularly distributed over dorsal surface; pseudotentacles orange with anterior black band and white tipsNarrow irregular banding of opaque white and outer orange semi-transparent bandEast-central Florida and the Florida Keys; Bermuda; Jamaica; South Carolina–Newman et al. (2000)P. fitae Soutullo et al., 2021Ivory yellowishLilac stripe gradually darkening into a dim violet bandAbsentBlack elongated stains distributed over body surfacePigmented band formed by thin purple borderPlaya Langosta and Playa Carbon, Costa Rica–Soutullo et al. (2021)P. flavomarginatus (Ehrenberg, 1831) †Sooty violetAbsentAbsentAbsentThree marginal lines compoased of outermost hyaline, middle orange, and innermost paler orange linesRed Sea near the Ras el Gusr Is., Saudi Arabia–Lang (1884)P. floridanus Hyman, 1955bBrown network on whiteAbsentAbsentIrregular row of orange dots interspersed among greyish-black markings extenging nearly to body margin; fine orange line running along marginAbsentAt some distance out in the Gulf od Mexico off the north-western coast of Florida (by dredging); US Virgin Islands; Belize; Honduras; Colombia; Dominica–Hyman (1955b); Bolaños et al. (2007)P. fragum sp. n.Translucent creamAbsentAbsentFour dark maculae in midline; large red maculae distributed radially along body marginAbsent100–180 m depth off Misaki, Japan–This studyP. fuscolineatus Dixit et al., 2017White to creamBrown longitudinal stripes; two black longitudinal stripes on both sides near body margin; all stripes joining at posterior endAbsentAbsentAbsentAndaman and Nicobar Islands, India–Dixit et al. (2017)P. giesbrechtii Lang, 1884 †PinkishLongitudinal blue and white or cream bands with single longitudinal yellow stripe at middleAbsentAbsentAbsentBay of Naples, Italy; Vietnam; Canary Archipelago; La Gomera; Canary Islands; Gulf of Antalya, Turkey–Lang (1884); Noreña et al. (2014); Teker et al. (2017)P. maculosus (Verrill, 1892)Pale, translucentAbsentAbsentPurplish or brown mottles or veins; usually a number of daker and more distinct brown small dots scattered over body centreDistinct radial spots along body marginWoods Hole, Cape Cod, Massachusetts, USA–Verrill (1892)P. meleagrinus (Kelaart, 1858)†WhiteReddish midline edged with black line; broad white stripes and light purplish streaksAbsentAbsentNarrow black marginCeylon–Kelaart (1858)P. moseleyi Lang, 1884Whitish or yelllowishAbsentAbsentDark purple round spots scattered over body; purple pseudotentaclesYellow bandGulf of Naples, Italy; the coasts of Catalonia, Spain; 5–10 m depth, Ria de Arosa, Galicia, Spain; Canary Archipelago–Lang (1884); Noreña et al. (2014); Cuadrado et al. (2017)P. nigricornus Schmarda, 1859†Reddish yellowAbsentAbsentNumerous dark-brown to black spotsBlack lineSouth Sea, Paita Bay, Peru–Schmarda (1859)P. panamensis Woodworth, 1894Reddish brown fading gradually towards margins (alchol preserved); irregular meshwork with colourless interspacesAbsentAbsentAbsentAbsentPanama–Woodworth (1894)P. pseudolimax Lang, 1884 †WhiteWide yellow band edged with narrow line at middle; black longitudinal line on both sides; narrow black line at outside of each black bandAbsentAbsentAbsentPosilipo, Gulf of Naples, Italy–Lang (1884)P. roseus Lang, 1884 †Pink to purpleWhite longitudinal stripesAbsentAbsentWhite lineGulf of Naples, Italy; Ria de Arosa, Spain–Lang (1884); Noreña et al. (2014)P. rubropunctatus Lang, 1884 †Pale and delicate white, becoming more intense at bulgeAbsentAbsentNumerous, dense, small, carmine-red spots scattered over body; milky-white dots scattered between larger red spotsAbsentGulf of Naples, Italy–Lang (1884)P. violaceus (Delle-Chiaje, 1822– 1829) †PurplishAbsentAbsentOrbicular spotsWhite bandGulf of Naples, Italy–Lang (1884)P. vittatus (Montagu,1815)Whitish or ivoryBlack, continuous stripes; black discontinuous lines between stripesAbsentAbsentAbsentNorth Atlantic coasts of the UK, France, Ireland, Scandinavia, Norway, and Denmark; the Mediterranean shores in Italy, Spain–Lang (1884); Noreña et al. (2014)P. zebra Hyman, 1955 a†Whitish or pale greyish brownAbsentNumerous irregularly black lines, that are slightly thickened at their endsWhite tips and white anterior border at pseudotentaclesAbsent3 m depth in the Gulf of Mexico, Florida; Jamaica–Hyman (1955a)
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†Species incertae sedis (Tyler et al. 2006–2024).