A systematic revision of the Shovel-nosed Salamander (Plethodontidae: Desmognathus marmoratus), with re-description of the related D. aureatus and D. intermedius
Author
Pyron, R. Alexander
0000-0003-2524-1794
rpyron@colubroid.org
Author
Beamer, David A.
0000-0003-2524-1794
rpyron@colubroid.org
text
Zootaxa
2023
2023-04-20
5270
2
262
280
http://dx.doi.org/10.11646/zootaxa.5270.2.5
journal article
255189
10.11646/zootaxa.5270.2.5
5df54694-df76-4304-8adc-c750a0c1c7eb
1175-5326
7850637
203D4821-2C0D-4ECB-9298-05EE363D1F05
Desmognathus aureatus
(
Martof, 1956
)
Leurognathus marmorata aureata
Martof, 1956
Leurognathus marmorata roborata
Martof, 1956
,
holotype
UMMZ 111568 by original designation, collected
18 September 1954
by “the Bernard Martof family,” type locality “Reed Creek, along Burrell Ford Road, 0.5 of a mile from its junction with Glade School Road, about
3.5 miles
northwest of Pine Mountain Community, Rabun County,
Georgia
;
2,350 feet
elevation.”
Paratypes
UMMZ 111569 (lot of
26 specimens
); same data. Informally synonymized with
L. marmorata
by
Martof (1962)
and resurrected by
Dubois and Raffaëlli (2012)
based on a suggestion by
Jones
et al.
(2006)
. Here designated a junior subjective synonym of
D. aureatus
.
Holotype
:
UMMZ 111566
by original designation, collected
11 September 1954
by “
Stephen
and
Andrew Martof
,” type locality “
Jarrard’s Creek
, 0.2 of a mile below its crossing of U.S.
Route
19, about 9 air miles north-northeast of
Dahlonega
,
Lumpkin County
, Georgia;
1,550 feet
elevation.”
Paratypes
:
UMMZ 111567
(lot of
20 specimens
); “data as for the holotype.”
Description:
After
Martof (1956)
, adults of this species have no vomerine teeth (versus presence in
Desmognathus intermedius
and
D. marmoratus
[some females]); ventral color-pattern pale or mottled (versus dark or black in other Blue Ridge lineages); and dark brown to black background of dorsum with dorsal color-pattern consisting of paired, golden, marbled or lichenous blotches (albeit less distinct in northeastern populations previously assigned to
L. m. roborata
Martof, 1956
). These characters should be re-evaluated for diagnostic consistency. In our sample, this is the smallest shovel-nosed species, with metamorphosed SVL =
34–73mm
. Based on our size-corrected linear morphometric analyses, this species can be distinguished from
D. intermedius
by a shorter trunk (AG in original measurements =
17–40mm
) and from
D. marmoratus
by a longer head (SG in original measurements =
8.1–17.1mm
). From
Martof (1962)
, females at sites in
Georgia
develop sexual maturity around
55–59mm
SVL, typically laying 27–
54 eggs
from May to July, with clutch size dependent on body size. Hatchlings are as small as
10–12mm
SVL and metamorphose at
25–38mm
(usually ~30) after 10–20 months, though up to three distinct size classes at some suggest possibly longer periods up to ~36 months. Larvae and adults are primarily insectivorous, likely preying opportunistically on available aquatic invertebrates (
Martof and Scott 1957
). Adults in some
Georgia
populations are occasionally bright yellow, a characteristic that apparently shifts rapidly in frequency within populations over short timescales (
Martof and Walton 1965
).
Range:
The Blue Ridge Mountains of northeastern
Georgia
, northwestern
South Carolina
, and small portions of the nearby border regions of
North Carolina
, in headwater streams of the Chattahoochee, Chattooga, and Tallulah River drainages (
Fig. 1
;
Voss
et al.
1995
;
Jones
et al.
2006
). Elevational range ~
400–1100m
.
Habitat:
As with all shovel-nosed salamanders, occurs almost exclusively in the rocky riffle zones of a fast-flowing, high-gradient mountain streams.
Etymology:
The specific epithet is a Latin singular adjective in the nominative case meaning “adorned with gold,” in reference to the dorsal coloration (
Fig. 7
).
Standard English Names:
For
Desmognathus aureatus:
Golden
Shovel-nosed Salamander (
Conant 1958
); for
Leurognathus marmoratus roboratus
Martof, 1956
: Husky Shovel-nosed Salamander (
Conant 1958
). We suggest that “Southern” Shovel-nosed Salamander is more appropriate.
Conservation:
This species is apparently widespread and abundant at numerous historical and recent sites across its range, a significant proportion of which is protected by state, federal, and private entities. Consequently, we suggest that it be considered “LC—Least Concern” based on available data (
Maes
et al.
2015
).
FIGURE 7.
An adult
Desmognathus aureatus
from Pruitt Creek (GA: Lumpkin), near the type locality. Note the brighter yellow or golden lichenous dorsal blotches. Photo courtesy of MAS.
Notes:
Implicitly synonymized with
Leurognathus marmoratus
(
Moore, 1899
)
by
Martof (1962)
. Indirectly suggested for resurrection by
Jones
et al.
(2006)
, though this was essentially ignored. Later explicitly resurrected by
Dubois and Raffaëlli (2012)
, though few subsequent authorities followed this arrangement. Part of the Nantahala clade (
Jones and Weisrock 2018
; Pyron
et al.
2020, 2022c) and the sister lineage of the Dwarf Black-bellied Salamander
Desmognathus folkertsi
Camp, Tilley, Austin, & Marshall, 2002
. The presence of the shovel-nosed phenotype in this lineage may have been transmitted to or from the Pisgah clade via an episode of ancient adaptive introgression (Pyron
et al.
2020).
Within the Pisgah clade,
Beamer and Lamb (2020)
and Pyron
et al.
(2020, 2022c) sampled specimens from the
type
localities of
Leurognathus marmorata intermedia
Pope, 1928
and
L. m. melania
Martof, 1956
, which were highly similar genetically and belonged to the
marmoratus
C lineage. Therefore, we conclude that
marmoratus
C should be referred to as
Desmognathus intermedius
(
Pope, 1928
)
, including
D. melanius
(
Martof 1956
)
in synonymy. Consequently, the species
D. melanius
recognized by
Frost (2019)
following
Dubois and Raffaëlli (2012)
and
Raffaëlli (2013)
is not valid but is instead preoccupied by: