Tadpoles of the United States and Canada: A Tutorial and Key

Ronald Altig¹, Roy W. McDiarmid², Kimberly A. Nichols³ and Paul C. Ustach⁴

DIVISION 6: PELOBATIDAE

KEY: FAMILIES	KEY: BUFONIDAE	KEY: RANIDAE
KEY: HYLIDAE	KEY: MICROHYLIDAE	TUTORIAL

SECTION 1. SIZE, BUCCAL ANATOMY, AND RANGE: Division 1, Sections 1-B and 3-D - [4] -

A.	to 100.0 TL; at least larger specimens with keratinized knob on roof of anterior part of buccal cavity; Mississippi River to Pacific Ocean

Spea (part) - Section 2

B.	< 35.0 TL; never with keratinized knob on roof of anterior part of buccal cavity; Great Plains east to Atlantic Ocean

Scaphiopus - Section 5

SECTION 2. TROPHIC MORPHOLOGY, LTRF, BODY SHAPE, AND COLORATION: Division 1, Sections 1-B and 3-D; Division 6, Section 1-A - > 100.0 TL; often with keratinized knob on roof of anterior part of buccal cavity; Mississippi River to Pacific Ocean - [5] -

A.

cannibal morphotype - immensely hypertrophied jaw musculature visible through skin produces large-headed appearance (= widest part of body at about plane of eyes); margin of upper jaw sheath with pronounced medial convexity (= cuspate), margin of lower sheath with medial concavity; LTRF typically 4/4 but variable and tooth ridges often sparsely populated; body notably depressed; coloration highly variable relative to turbidity of habitat, but always uniform, iridophore pigmentation often prevails in life; to 100 TL

Section 3

B.

non-cannibal morphotype - jaw musculature normally proportioned, widest part of body at about middle of abdomen; margins of upper and lower jaw sheaths follow uniform track; LTRF typically 4/4 but variable, tooth rows usually well formed; body globular; coloration highly variable relative to turbidity of habitat, but always uniform, iridophore pigmentation often prevails; tail tip bluntly pointed; to 80 TL

Section 4

SECTION 3. RANGE: Division 1, Sections 1-B and 3-D; Division 6, Sections 1-A and 2-A - to 100.0 TL; at least larger specimens with keratinized knob on roof of anterior part of the buccal cavity; Mississippi River to Pacific Ocean; cannibal morphotype - [2, in sympatry] -

A.	most of western Great Plains from Trans Pecos area of Texas west into Arizona and adjacent Utah and north to southern Alberta and adjacent British Columbia (sympatric: Scaphiopus couchii, S. hurterii, and Spea multiplicata**)

Spea bombifrons (part) [B]

B.	Central Valley of California and west (sympatric: none)

Spea hammondii (part) [B]

C.	Great Basin from south-central British Columbia to southern Nevada and east through Idaho and Utah, mostly allopatric to all other pelobatids (sympatric: Spea multiplicata)

Spea intermontana (part) [B]

D.	eastern half of Texas west through most of Arizona (sympatric: Scaphiopus couchii, Spea intermontana**, and S. bombifrons**)

Spea multiplicata (part) [B]

SECTION 4. RANGE:Division 1, Sections 1-B and 3-D; Division 6, Sections 1-A and 2-B - to 100.0 TL; at least larger specimens with keratinized knob on roof of anterior part of buccal cavity; Mississippi River to Pacific Ocean; non-cannibal morphotype - [2, in sympatry] -

A.	most of western Great Plains from Trans Pecos area of Texas west into Arizona and adjacent Utah and north to southern Alberta and adjacent British Columbia (sympatric: Scaphiopus couchii, S. hurterii, and Spea multiplicata**)

Spea bombifrons (part) [B]

B.	Central Valley of California and west (sympatric: none)

Spea hammondii (part) [B]

C.	Great Basin from south-central British Columbia to southern Nevada and east through Idaho and Utah, mostly allopatric to all other pelobatids (sympatric: Spea multiplicata)

Spea intermontana (part) [B]

D.	eastern half of Texas west through most of Arizona (sympatric: Scaphiopus couchii, Spea intermontana**, and S. bombifrons**)

Spea multiplicata (part) [B]

SECTION 5. LTRF, COLORATION, AND RANGE: Division 1, Sections 1-B and 3- D; Division 6, Sections 1-B - < 35.0 TL; never with keratinized knob on roof of anterior part of buccal cavity; Great Plains to Atlantic Ocean - [4] -

A.	LTRF 4/4; brassy in life with haphazard black marks on distal third of tail muscle; southwestern Oklahoma south to Gulf of Mexico and west to southeastern California (sympatric: Scaphiopus hurterii, Spea bombifrons, and S. multiplicata)

Scaphiopus couchii [B]

B.	LTRF 6/6; brown to bronze with no contrasting markings on tail muscle; northeastern third of Arkansas and adjacent Missouri and much of area east of Mississippi River south of latitude of southern Ohio (sympatric: none)

Scaphiopus holbrookii [A]

C.	LTRF 6/6; brown to bronze with no contrasting markings on tail muscle; eastern third of Texas and Oklahoma and adjacent Arkansas and Louisiana (sympatric: Scaphiopus couchii and Spea bombifrons)

Scaphiopus hurterii (not illustrated) [C]

Back to Division 1: Families