Those of you who bore with me through my (admittedly rather
personal) essay last month [2] will not be surprised to learn that between
the fall of 1973 and the spring of 1977, I spent most of my spare time loitering
about the periodicals-currently-received section of the Virginia Tech library,
waiting for the new issues of Nautilus, Malacologia, and Malacological Review
to hit the news stands. And when my
eager eyes first drank in that (really rather beautiful) 1975 paper by a
graduate student up in Ann Arbor named George A. Te [3], I knew I had found
the man who could, at long last, scratch my Physa itch.
Looking back with the benefit of 40 years’ perspective, George
Te’s “Michigan Physidae” may have represented the zenith of classical malacology
in North America – impressively rigorous in its systematics, pristinely
innocent of genetics. His input data
were 3,888 museum shell lots and 252 alcohol lots, cataloged under 34 specific
or subspecific nomina. He analyzed each
shell lot subjectively but critically, developing an elaborate scoring system
of about 30 characters, for example shell shape = elongate-slender, elliptical-subcylindrical,
ovate-globose, and so forth. A single
individual from each alcohol lot was dissected to reveal the penial complex [4], which was scored by four additional characters. His output data were a (much shorter!) list
of 6 species and 8 subspecies confirmed from the waters of the state of Michigan,
7 nomina lowered into synonymy, and 13 nomina subtracted by correction of range
or identification.
Among the strengths of Te’s 1975 work were his excellent
historical review of the taxonomy of the Physidae [5], his extensive tabulations
of the shell and penial character states for the 14 taxa he considered valid
elements of the Michigan fauna, a plate of small (but serviceable) shell
photos, and a (remarkably ambitious) dichotomous key to the shell
morphology. Perhaps his most significant
contribution was a formal taxonomy for physid penial morphology, which still remains
useful today [below, note 6].
Those same 40 years of hindsight also make it easy to find fault
with George Te’s paper on a number of grounds, however. He studied “museum lots,” not
populations. There is (almost) no
evidence that Te recorded any observations on the living creatures themselves,
or indeed that he conducted any fieldwork whatsoever [7]. And Te’s species concept was rigidly
typological, betraying no hint that he understood the concept of variance,
either within populations or between them.
So (for example) the shell length for 623 museum lots of Physa integra was
given as 12.7 mm.
The worst consequence of Te’s typological species concept –
which would ultimately render his 1978 dissertation virtually useless – seems
to have been that he did not feel it necessary to provide locality data (or
equivalently, catalog number) for any specimen he ever examined [8]. I understand that if all 623 of his lots of Physa
integra did indeed bear elongate-ovate shells 12.7 mm in standard length, it
will not matter where any particular individual specimen of P. integra was
collected. But they didn't, and it
does. A lot.
Nevertheless, against the background of the medieval ignorance
that prevailed regarding the North American Physidae prior to 1975, George Te’s
Michigan paper was a tremendous advance.
Physids are the most widespread freshwater gastropod in the waters of
eastern North America. And all across
this great country of ours, the environmental movement was dawning. The National Environmental Policy Act was
passed in 1970, the Clean Water Act in 1972 [9], and the Endangered Species
Act in 1973. Agencies and industries
were suddenly being held accountable for environmental “impacts” of all sorts,
but a secondary trade had not as yet arisen to meet the demand for environmental
support and consultation. So contracts
for environmental work flooded into the universities, which were the only place
where any technical expertise in addressing such questions resided. Expertise that included, I suppose, that of a
20-year-old undergraduate biology major at Virginia Tech.
Meanwhile, back in southern Virginia, ten years of
controversy had already swirled around Appalachian Power Company’s “Blue Ridge
Project,” a double-dam, pumped-storage facility on the New River straddling the
North Carolina line [10]. So in 1975, the
Virginia Tech Center for Environmental Studies issued me a pair of boots, a
pair of buckets, a kick-net and a pickup truck [11]. And off I went up the New River Valley,
sampling 89 sites and ultimately identifying 6 unionid species, 4 pisidiid
species, and (approximately) 10 species of freshwater snails.
By this stage of my young career I was familiar with Baker’s
(1911) lymnaeid monograph [12] and his (1945) planorbid plates [13], as well as
Basch’s excellent (1963) work on the ancylid limpets [14]. And now, just when I needed him the most, a
promising young graduate student in Ann Arbor threw me a lifeline on the
Physidae.
I first wrote George Te in March of 1976, inquiring whether
he might be willing to examine my samples of physids from southern Virginia. His reply was prompt, courteous, and affirmative. And over the next five months, we exchanged a
pleasant correspondence focusing primarily on the New River Physa, which he
found most interesting. He recognized
two species – Physa hendersoni widespread throughout the upper (soft water)
mainstem and tributaries, and Physa pomilia in scattered hard water sites
downstream. George Te considered the
occurrence of P. hendersoni in the upper New River especially interesting, as
“little is known about (its) range beyond its type locality in South
Carolina.” I accepted his
identifications as gospel, of course, transferring both to my (1977)
undergraduate honors thesis [15], and to the (1982) paper I published in
Freshwater Biology with my adviser, E. F. Benfield [16].
In retrospect, I cannot imagine how George Te’s
identifications of my New River Physa samples could have been more wrong. The physid populations widespread in soft
waters upstream are P. acuta, and the scattered hard water populations
downstream are P. gyrina. Physa hendersoni
is a junior synonym of P. pomilia [17], and is entirely absent from the New
River drainage, under all aliases, as far as is known today.
But science is not about being correct, it is about being
testable. And George Te’s 1975 Michigan
paper, even without genetics, field observations, or indeed locality data,
was the first scientific treatment of the North American Physidae since the
dawn of the modern synthesis. The
photos, dichotomous key, and tabulations of character states it contained were
sufficient to allow Amy Wethington and myself to return to Michigan in 2003 and
re-identify multiple biological populations of the typological species Te
recognized in 1975. These we used to
calibrate the genetic tools and breeding studies we were developing to conduct
a fresh review of the family. No, there
are not six valid biological species of physids in Michigan [18]. But that is not important.
And George Te’s research contributions were by no means
complete with his 1975 paper. His
higher-level taxonomy was still very traditional in 1975, all Michigan species
referred to the large, inclusive genus Physa favored by Bryant Walker [19] and
earlier workers, except the oddball Aplexa hypnorum. Where did that unfortunate generic nomen “Physella”
come from? Tune in next time!
Notes
[1] George Te (1946 – 2013) Poughkeepsie Journal,
12Nov13. [html]
[3] Te, G. A. (1975) Michigan Physidae, with systematic
notes on Physella and Physodon (Basommatophora: Pulmonata). Malacological Review 8: 7-30.
[4] Te’s (1975) paper did not include data on any aspect
of the anatomy other than penial complex.
But he added (promisingly) that the types of penial sheaths “correlate
with observations on differences in the renal complex, mantle digitations,
mantle border, radula, and other anatomical structures (Te, unpubl).”
[5] Te’s thorough review of the decades of abject
confusion surrounding the nomen “Physella” should be required reading for any
taxonomist who has ever considered subdividing the Physidae.
[6] The image with this month's post depicts Te’s 1975 diagrams of the four penial complex types: Aplexa-type,
Type-a, Type-b, and Type-c. The differences that Te perceived among the various "subtypes" are not significant.
[7] Well, that’s a bit unfair. Te mentioned that he made “direct field
collections” (locality unspecified) in his discussion of penial morphology, and
thanked P. T. Clampitt “for helping me collect P. parkeri and P. integra at
Douglas Lake” in his acknowledgements.
But any field observations he may have made apparently had zero
influence on his 1975 paper. In Table 4,
for example, we read that the habitat preference of 171 “museum lots” of Aplexa
hypnorum was “woods pool,” and the habitat preference of 343 museum lots of P.
gyrina was “pools and ditches,” and so forth.
[8] We will
return to the subject of George Te’s (1978) dissertation next month.
[9] The Clean
Water Act at 40 [7Jan13]
[10] APCO’s Blue Ridge Project was ultimately stopped in
late 1976, when a 26.5 mile section of the New River in North Carolina was
added to the National Wild and Scenic Rivers system. Here’s an excellent thesis reviewing the controversy:
- Woodard, R. S., Jr. (2006) The Appalachian Power Company along the New River: The defeat of the Blue Ridge Project in historical perspective. M.A. Thesis, Virginia Tech, Blacksburg. 139 pp. [pdf]
[11] Those were the glory days! The peg board behind the desk at John
Cairns’ Center For Environmental Studies must have held keys to at least 20 vehicles. And even undergraduates could check one out,
with a state gas card in the glove compartment.
But my adviser Fred Benfield, said this: “If you wreck that truck, Boy,
just keep going. Never come back.”
[12] Baker, F.C. (1911) The Lymnaeidae of North and Middle
America. Recent and fossil. Chicago Academy of Sciences Special Publication No.
3. 539 pp.
- See, The Legacy of Frank Collins Baker [20Nov06]
[13] Baker, F.C. (1945) The molluscan family Planorbidae.
Collation, Revision, and Additions by H.J. Van Cleave. University of Illinois Press.
Urbana, Illinois. 530 pp.
- See, The Classification of the Planorbidae [11Apr08]
[14] Basch, P.F. (1963) A review of the recent freshwater
limpet snails of North America (Mollusca: Pulmonata). Bull. Mus. Comp. Zool.
Harvard Univ. 129: 399–461.
[15] Dillon, R. T., Jr. (1977) Factors in the distributional
ecology of upper New River mollusks (Va/NC).
Unergraduate Honors Thesis, Virginia Tech, Blacksburg. [pdf]
[16] Dillon, R.T. and E. F. Benfield (1982) Distribution of
pulmonate snails in the New River of Virginia and North Carolina, U.S.A.:
Interaction between alkalinity and stream drainage area. Freshwater Biology 12:
179-186. [pdf]
[17] Dillon, R. T., J. D. Robinson, and A. R. Wethington
(2007) Empirical estimates of
reproductive isolation among the freshwater pulmonates Physa acuta, P. pomilia,
and P. hendersoni. Malacologia 49: 283 -
292. [pdf]
[18] Dillon, R. T.,
and A. R. Wethington (2006) The Michigan
Physidae revisited: A population genetic study.
Malacologia 48: 133 - 142. [pdf]
[19] Walker, B.
(1918) A Synopsis of the Classification of the Freshwater Mollusca of North
America, North of Mexico. Misc. Pubs., no. 6. Ann Arbor: University of Michigan
Press.
- See, Bryant Walker’s Sense of Fairness [9Nov12]
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