A review of the genus Tragidion Audinet-Serville, 1834 (Coleoptera: Cerambycidae: Cerambycinae: Trachyderini)
Author
Swift, Ian
Author
Ray, Ann M.
text
Zootaxa
2008
1892
1
25
journal article
10.5281/zenodo.274503
4589ed63-3240-4b9a-a152-1e1cb2504f3c
1175-5326
274503
Tragidion annulatum
LeConte
(
Figs 1
C–D, 7C)
Tragidion annulatum
LeConte, 1858
: 83
;
Leng, 1886
:81
.
Type
locality: Sonora,
Mexico
(probably an error).
Tragidion annulatum
var.
peninsulare
Schaeffer, 1908
:339
;
Casey, 1912
: 321
.
Type
locality: San Felipe, Baja California,
Mexico
.
New synonymy
.
Tragidion peninsulare peninsulare
:
Linsley, 1940
: 137
;
Linsley, 1942
: 60
;
Hovore, 1988
:28
Tragidion peninsulare californicum
Linsley, 1940
: 137
.
Type
locality: Paradise Valley, Kings River, Kern County, California,
USA
.
New synonymy
.
Material examined
:
49 specimens
, including one
lectotype
and two
paralectotypes
at
MCZC
.
Diagnosis
.
Tragidion annulatum
is fairly distinctive within the genus. It most closely resembles
T. deceptum
. From
T. deceptum
, it can be distinguished by the elytral costae which extend to the apex; the dark basal elytral band which is very narrow and does not exceed the scutellum; and the distinctive bright metallic blue reflections of the pubescence on the venter and metatibia.
Linsley (1940
,
1942
,
1962
) had difficulty interpreting
T. annulatum
, and incorrectly assigned other names to the California populations. The incorrect
type
locality may have added to his confusion (see below). In Linsley’s treatment (1962),
T. annulatum
is listed as occurring in the lowland deserts of the southwest.
Tragidion annulatum
, however, is common along the western coast of North
America
, inhabiting deserts only in the Baja Peninsula.
FIGURE 6.
Distribution map of
Tragidion
spp. A,
Tragidion armatum
; B,
T
.
bicolor
; C,
T
.
carinatum
; D,
T
.
coquus
; E,
T
.
dichromaticum
.
FIGURE 7.
Distribution map of
Tragidion
spp. A,
Tragidion agave
; B,
T
.
gracilipes
; C,
T
.
annulatum
; D,
T
.
deceptum
; E,
T
.
densiventre
; F,
T
.
auripenne
.
Based on an examination of all available specimens, the primary characters used to separate Linsley’s
californicum
subspecies from the nominate form – smaller size and narrower tarsi – are entirely clinal and allometric, as the overall size of specimens decreases farther north. Therefore, material from northern Baja California,
Mexico
and California,
USA
are considered to represent
T. annulatum
.
Discussion
. The International Code of Zoological Nomenclature (ICZN, 1999) in Article 74.7.3 specifically states that designations of
lectotypes
after 1999 must “contain an express statement of the taxonomic purpose of the designation”. The
lectotype
designation herein for
T. annulatum
is to assign a single specimen of this species as the sole name-bearing specimen to stabilize future nomenclature. There are three specimens labeled as
T. annulatum
LeConte
in the MCZC, none of which is designated as a
type
. Therefore, a representative was selected, and a label stating “
LECTOTYPE
Tragidion annulatum
LeConte Ian
Swift, 2008
” was affixed to that specimen.
LeConte (1858)
lists “Sonora,
Mexico
” as the
type
locality for this species. However, of the
49 specimens
examined for this study, we have not seen any
T. annulatum
from Sonora or anywhere in mainland
Mexico
. While it may be possible that this species occurs in that region, the
type
series matches very closely specimens from southern Baja California Sur,
Mexico
, and this is likely where the
type
series was collected. Therefore, under recommendation 76A.2 of the ICZN, the
type
locality listed for this species is considered an error, and should be amended to indicate Baja California Sur,
Mexico
.
Distribution
(
Fig. 7
C). Throughout the western coast of North
America
including California,
USA
, and the states of Baja California, and Baja California Sur,
Mexico
. This species occurs in a wide variety of habitats, including Sonoran Desert in the Baja Peninsula, and in tropical deciduous forest and montane oak woodland in the cape region. In California, it is found in many different habitats, including chaparral, oak, and conifer woodlands.
Ecology
.
Linsley (1962)
and
Hovore and Giesbert (1976)
summarized the ecology of this species in part. Individuals of
T. annulatum
are strongly attracted to brushfires and burning vegetation (
Hovore and Giesbert 1976
). Adults have been observed flying into more than 25 brushfires throughout the southern California region from
1994–2007
, and the larval workings have been observed at most other burned sites (pers. obs.). During some of these brushfires, individuals landed on still-burning and smoldering shrubs, causing their legs and abdomens to melt to the surface of the branches. At several post-burn sites, the melted bodies of this species were common on the charred branches of their hosts. Females have been observed ovipositing on woody shrubs that have been burned. This behavior is generally similar to that of some species in the buprestid genus
Melanophila
Eschscholtz (
Sowards
et al
., 2001
)
. However,
Tragidion
does not possess infra-red receptors used by
Melanophila
to locate appropriate host plants (pers. obs.). The means by which
T. annulatum
detect burning vegetation is unknown. Given the abundance of
T. annulatum
at burned sites, and the frequency and importance of brushfires in Mediterranean shrublands in California and northern Baja California (
Keeley 2006
),
T. annulatum
is likely an important member of the insect fauna associated with the decomposition of burned woody material. The larval period is one year in all laboratory-reared samples. The larvae mine galleries throughout the branches of their host, pupating in a chamber parallel to the grain.