|1||External copulatory gland pores on venter, located about 10-11 annuli posterior to the male gonopore||2*|
|- No copulatory gland pores 10-11 annuli behind male gonopore||5*|
|2||Gonopores separated by 2-2.5 annuli||3*|
|-Gonopores separated by more than four annuli, usually five||4*|
|3||Dorsum with about 21 metameric red or orange dots at mid-line:|
With 24 copulatory gland pores (two rows of two groups, containing six gland pores each); known only from eastern Massachusetts (Smith 1977)
|Macrobdella sestertia Whitman, 1886|
|-Dorsum lacking red or orange dots: |
With eight copulatory gland pores (two rows of four); widely distributed throughout southeastern states.
|Macrobdella ditetra Moore, 1953|
|4||Four copulatory gland pores (two rows of two): |
Widely distributed throughout northern states and Canada.
|Macrobdella decora (Say, 1824)|
|- Six copulatory gland pores (three transverse rows of two each): |
This form occurs at the southern periphery of the range of its very closely allied species Macrobdella decora, near the Missouri-Kansas border; Parallel modifications of the copulatory pores occur at the extreme southern Appalachian end of the range of M decora (Sawyer and Pass 1972).
|Macrobdella diplotertia Meyer, 1975|
|5||Glandular area around gonopores, the latter obscured by deep copulatory depressions: |
Dorsum with a yelllow or brown stripe; gonopores separated by 3-4 annuli but difficult to see; widely distributed in southern states; A related form, the genotype Philobdella floridana (Verrill 1874), is inadequately distinguished from P gracilis, with which it is probably conspecific; type locality; Lake Okeechobee, Florida
|Philobdella gracilis Moore, 1901|
|- No glandular area around gonopores; gonopores distinct and separated by five or more annuli||6*|
|6||Gonopores separated by five (or 5.5) annuli |
Female gonopres small and not nipple-like
|- Gonopores separated by seven (or 6.5) annuli: |
Female gonopore large, conical, nipple-like in adults, flattened in juveniles
|Haemopis septagon Sawyer and Shelley, 1976|
|7||27 distinct annuli from oral cavity to annulus (XIb6) bearing male gonopores, annuli VIIa3 and VIIIa1 completely subdivided ventrally||Haemopis terrestris (Forbes, 1890)|
|-25 distinct annuli from oral cavity to annulus (XIb6) bearing male gonopores, annuli VIIa3 and VIIIa1 not subdivided ventrally||8*|
|8||With jaws and teeth||9*|
|- Lacking teeth and distinct jaws||11*|
|9||Dorsal surface with median dark stripe: |
Body firm in life; juveniles with metameric dark transverse bands.
|Haemopis kingi Mathers, 1954|
|- No mid-dorsal dark stripe |
Irregularly pigmented or unicolour; body limp in life.
|10||Flexion of penis sheath at XII-XIII: |
Caudal sucker large, about 0.75 width of body; recorded only from Iowa and Minnesota.
|Haemopis lateromaculata Mathers, 1963|
|-Flexion of penis sheath at XVII (XVI-XVIII): |
Caudal sucker relatively small, about 0.5 width of body; very common and widely distributed throughout northern United States and Canada; two colour morphs; (i) olive green with heavy mottling dorsally and ventrally; (ii) uniform slate grey with a few irregular black blotches, resembling H grandis
|Haemopis marmorata (Say, 1824)|
|11||Margin of oral sucker thick, rounded, aperture transverse, the lower margin anteriorly convex |
Lower surface of velum closely and finely papillate; pharynx with 15 longitudinal folds; flexion of penis sheath at XVI.
|Haemopis plumbea Moore, 1912|
|-Margin of oral sucker thin, aperture elongate and arched, the lower margin sharply concave: |
Lower surface of velum smooth; pharynx with 12 longitudinal folds; flexion of penish sheath at XVI
|Haemopis grandis (Verrill, 1874)|
|1||Ejaculatory duct with a preatrial loop extending anteriorly to ganglion XI||2*|
|-Ejaculatory duct without a preatrial loop extending to ganglion XI||8*|
|2||All mid-body annuli distinctly subdivided: |
Atrial horns spirally coiled like a ram's horn; distributed only in the northern tier of states and Canada.
|Erpobdella obscura Verrill, 1872|
|-All mid-body annuli not subdivided |
Atrial horns simple, not spirally coiled
|3||Gonopores separated by two annuli, male gonopores in furrow||4*|
|-Gonopores separated by 2.5 or more annuli, male usually on annulus and not in furrow||5*|
|4||Atrial horns anteriorly directed, with tendency toward the medial: |
With two or four longitudinal rows of black pigment concentrations; male gonopore remarkably large in adults; a very common species throughout United States, Canada, and into Mexico; E montezuma from Arizona has posterior crop caeca (Davies, Singhal, and Blinn, 1985).
|Erpobdella punctata (Leidy, 1870)|
|- Atrial horns directed anteriolaterally, no tendency toward the medial: |
A poorly charaterized Californian species; in spite of its name some, especially young, individuals possess three pairs of eyes (Gadler and Olson, 1985); This has no bearing on the validity of its name.
|Erpobdella anoculata (Moore, 1898)|
|5||Eyes three pairs: |
Male pore very large, on annulus; a coastal plain form of E punctata punctata, from Carolinas
|Erpobdella coastalis Sawyer and Shelley, 1976|
|6||Eyes four pairs: |
Male pore only moderately large; from northern states and Canada.
|7||Dorsum with variable dark mid-dorsal stripe: |
Dorsum greenish, heavily mottled; gonopores separated by 3.5-4 annuli.
|Erpobdella dubia (Moore and Meyer, 1951), n comb.|
|- No mid-dorsal stripe: |
Dorsum unpigmented or colour uniformly smokey grey; gonopores separated by 2.5-3.5 annuli.
|Erpobdella parva (Moore, 1912),|
|8||Gonopores separated by two annuli||9*|
|- Gonopores separated by three or four annuli||10*|
|9||Atrial horns directed medially: |
Body cream-coloured with scattered small black chromatophores irregularly dispersed, not metameric; especially pigmented around mouth; mouth large, elliptical, with thickened anterior lips; typically found in coastal plain of Carolinas
|Erpobdella melanostoma Sawyer and Shelley, 1976|
|- Atrial horns directed anteriorly or laterally, not distinctly medially: |
Body uniformly smokey grey, lacking pigment entirely or sometimes with minute black pigment; occurs in northern states and Canada; A closely related form, E bucera Moore 1949, is localized in south-eastern Michigan; atrial horns projecting more laterally than E fervida
|Erpobdella fervida (Verrill, 1874)|
|10||Gonopores separated by three annnuli:||Erpobdella microstoma (Moore, 1901)|
|- Gonopores separated by four annuli:||Erpobdella tetragon Sawyer and Shelley, 1976|
|1||Eyes four pairs (Theromyzon) |
Three nominal species recognized here based on number of annuli between gonopores; in need of anatomical examination of the vaginal region of the female system (see Livanow 1902).
|- Eyes one, two or three pairs||4*|
|2||Gonopores separated by two annuli:||Theromyzon bifarum|
|- Gonopores separated by three or four annuli||3*|
|3||Gonopores separated by three annuli: |
The common species of the western United States and Canada.
|-Gonopores separated by four annuli: |
Common in Europe but its presence in North America requires re-evaluation based on criteria other than gonopores.
|Theromyzon tessulatum (OF Muller, 1774)|
|4||Mid-body segments biannulate: |
Caudal sucker large, conspicuous; known from mountains of North and South Carolina; permanent parasites on salamanders.
|Placobdella biannulata (Moore, 1900)|
|- Mid-body segments tri-annulate||5*|
|5||Eyes three distinct pairs |
Placobdella hollensis has accessory eyes and not included here.
|-Eyes one or two pairs||8*|
|6||Gonopores share a common pore: |
Three pairs of eyes, with a significantly smaller space between the eyes of the first pair than that between pairs 2 and 3; size small, less than 15 mm at rest; egg sacs attached directly to venter; colour whitish; six pairs crop caeca; A closely related form, A swampina (Bosc, 1802), lives in coastal Carolinas (Sawyer and Shelley 1976).
|Alboglossiphonia heteroclita (Linnaeus, 1761)|
|- Gonopores separated by two annuli |
Three pairs of eyes, all about equidistant from each other; size moderate, about 25 mm; egg sacs attached to substrate; darkly pigmented, with some dorsal papillae; seven pairs crop caeca; two conspicuous paramedian lines of brown pigmentation.
|7||Dorsum with conspicuous tubercles on second (2a) and third (a3) annuli of each mid-body segment: |
In North America known only from Alaska and British Columbia (Klemm 1981)
|Glossiphonia verrucata (Fr Muller, 1844)|
|-Dorsum relatively smooth, lacking tubercles on the third (a3) annulus: |
Common throughout North America except in southeastern states; this species, originally described as elegans Verrill, 1872, differs from its European namesake by having seven, instead of six, pairs of crop caeca.
|Glossiphonia complanata (Linnaeus, 1758).|
|8||Anterior sucker distinct from body |
Temporary parasites of fish (Shelley and Braswell 1981)
|- Anterior sucker not distinct from body||10*|
|9||Dorsum with three prominent ridges or keels:||Placobdella montifera Moore, 1906|
|- Dorsum smooth, lacking ridges:||Placobdella nuchalis Sawyer and Shelley, 1976|
|10||Eyes distinctly separated, usually by the diameter of one eye or more |
Crop caeca six or fewer pairs; no mycetomes; predaceous on invertebrates; eyes single, not compound; gonopores separated by one or no annuli.
|-Eyes close together or touching |
Crop caeca seven pairs; one pair mycetomes; parasitic on vertebrates; eyes in some species compound; gonopores separated by two annuli.
|11||Brown plaque (=scute) in mid-dorsal neck region: |
Nearly indisitinguishable from the European H stagnalis
|Helobdella modesta Verril|
|- No plaque in neck region||12*|
|12||Gonopores share a common pore: |
Dorsal and ventral surfaces heavily pigmented with uniform greyish-blue chromatophores and with thin dark paramedial lines extending to neck region; body opaque; dorsum smooth; a northern species widely distributed throughout Canada, and in Michigan
|Marvinmeyeria lucida (Moore, 1954)|
|- Gonopores separated by one annulus||13*|
|13||Crop caeca represented only by one short posterior pair ('post-caeca'), to XX/XXI: |
Body elongated, subcylindrical; lateral margins of body almost parallel; translucent, unpigmented body; caudal sucker small, terminal.
|Helobdella elongata (Castle, 1900)|
|-Crop caeca with six pairs crop caeca |
Body leaf-shaped to sublanceolate; caudal sucker ventral
|14||Dorsum with distinct papillae or tubercles||15*|
|-Dorsum smooth, lacking papillae or tubercles||16*|
|15||Dorsum roughly and heavily papillated: |
Dorsum with many whitish, rounded papillae arranged in 5-9 longitudinal series on each neural (a2) annulus; occurs in Great Lakes region.
|Helobdella papillata (Moore, 1906)|
|- Dorsum typically with three series of small black-tipped papillae: |
A notoriously variable species representing a complex of forms; typically with four series of metameric white dots on neural annulus external to papillae; no mid-dorsal dots; atypical forms with longitudinal stripes of with reduced number of papillae; Often given the name H triserialis which is strictly endemic to South America.
|Helobdella papillata (E Blanchard, 1849)|
|16||Dorsum with distinct transverse pigment patterns: |
Dorsum with transverse rusty-brown bands alternating with white bands, the latter consisting of 8-10 confluent white dots on neural annulus; no longitudinal pattern; pigment fades in ethanol; known from western Great Lakes states
|Helobdella transversa Sawyer, 1972|
|- Dorsum with longitudinal pigment patterns: |
Dorsum with six major longitudinal white stripes alternating with six coffee-brown stripes, including a mid-dorsal band; no transverse pattern; pigment remaining after preservation in ethanol; a variable species inadequately distinguished from Helobdella triserialis complex with which it is closely allied.
|Helobdella fusca (Castle, 1900)|
|- Dorsum with longitudinal pigment patterns: |
Dorsum with fine coffee-brown stripes, excluding a mid-dorsal band; no transverse pattern
|Helobdella lineata (Verril)|
|17||Salivary glands diffuse, in anterior two-thirds of body |
Caudal sucker typically modified for semipermanent attachment to host (ie large, on peduncle or with rim of specialized papillae); body typically rounded, soft-bodied, unicoloured; semipermanent parasites on fish or amphibians.
|- Salivary glands compact, typically two pairs which insert at base of proboscis |
Caudal sucker not remarkable, ventral; body typically flattened, firm-bodied and with distinct pigment patterns; temporary parasites on amphibians and reptiles.
|18||Anus anteriorly displaced, at XXIII/XXIV: |
Permanent parasite in gill-chamber of fish, especially the drum, Aplodinotus grunniens; caudal sucker set off from body by a narrow peduncle.
|Placobdella pediculata (Hemingway, 1908),|
|- Anus in normal position on segment XXVII |
Caudal sucker relatively enlarged, rim moderately thick, bulbous and set off from body by a short peduncle.
|19||Rim of caudal sucker with about 30 retractile digitate processes which when everted project finger-like along inner margin of sucker cavity: |
Usually found in gill-chambers of fish; mid-body segments three-annulate with tendency toward secondary subdivision; An aberrant form, A annectens Moore 1906, is characterized by about 60 digitiform processes, but has not been found since original description
|Actinobdella inequiannulata Moore, 1901|
|-Rim of caudal sucker lacking digitate processes: |
Known only from Ozark hellbender Crypotbranchus in Missouri.
|Actinobdella cryptobranchii (Johnson and Klemm, 1977)|
|20||Accessory eyes present: |
Two pairs of variable concentrations of dark pigment situated two and five annuli behind the single functional pair of eyes, giving the impression of three pairs of eyes
|Placobdella hollensis (Whitman, 1892)|
|- No accessory eyes||21*|
|21||Dorsum with conspicuous white genital and anal patches |
White ring in neck region
|- Dorsum without white patches||24*|
|22||Dorsum smooth, no papillae or tubercles |
|-Dorsum with three series of usually dark-tipped papillae: |
Body convex, thick, opaque; a variable species, incompletely characterized; known hosts: fish (Amin 1981).
|Placobdella phalera (Graf, 1899), n comb|
|23||Five longitudinal rows of white prominences surrounded by yellowish dots equidistant longitudinally and transversely; |
No true dark-tipped papillae; body ovate-lanceolate; known from Michigan.
|Placobdella michiganensis (Sawyer, 1972)|
|-Lacking the five longitudinal rows of white prominences: |
No true dark-tipped papillae; body lanceolate; lightly pigmented with small brown, cutaneous chromatophores; or pigmented with a broken longitudinal median stripe and two rows of submarginal spots; widespread in south-eastern United States.
|Placobdella translucens Sawyer and Shelley, 1976|
|24||Dorsum smooth, with no (or only inconspicuous) papillae||25*|
|- Dorsum conspicuously papillated, particularly evident at mid-dorsal line||26*|
|25||Dorsum with a vague, dark median stripe: |
With two paramedial pairs of yellowish metameric spots; venter not striped; commonly encountered on mating amphibians in early spring, in woods ponds of northern United States and Canada
|Placobdella picta (Verrill, 1872), n comb|
|- Dorsum lacking dark median stripe: |
Venter with 8-12 bluish-green longitudinal stripes; dorsal pigmentation variable; typically encountered on turtles but often free-living
|Placobdella parasitica (Say, 1824)|
|26||Dorsum rough, entirely covered with numerous papillae, usually varying in size or randomly arranged: |
Dorsum usually with a brown band at mid-dorsal line, interrupted 4-5 times; venter unstriped, with scattered dark chromatophores or plain; typical of the northern United States and Canada
|Placobdella ornata (Verrill, 1872)|
|-Dorsum less rough, not entirely covered with papillae; larger papillae in 5-7 longitudinal rows||27*|
|27||Venter with about eight bluish longitudinal stripes; |
Body ovate-lanceolate; dorsum with a vague, median, longitudinal stripe, contained in a wider bluish stripe; the two pairs of salivary glands enter base of proboscis independently; widely distributed (Davies and Wilkialis 1980; Sawyer and Shelley 1976).
|Placobdella papillifera (Verrill, 1872)|
|- Venter plain or with fine black chromatophores: |
Body lanceoloate; typically with narrow dark mid-dorsal stripe which is usually continuous; the two pairs of salivary glands enter base of proboscis via a common duct; typically found in southeastern United States, where it replaces P ornata: sometimes parasitic on alligators (Forrester and Sawyer 1974)
|Placobdella multilineata Moore, 1953|