Revision of the new world species of Hylurgops LeConte, 1876 with the description of a new genus in the Hylastini (Coleoptera: Scolytinae) and comments on some Palearctic species
Author
Mercado-Vélez, Javier E.
Author
Negrón, José F.
text
Zootaxa
2014
3785
3
301
342
journal article
46054
10.11646/zootaxa.3785.3.1
f3421d1a-3854-42da-95b9-5b47147f25ae
1175-5326
252614
6D6FCCF0-DA35-4F72-9420-07FDF9158E3F
Pachysquamus subcostulatus
(
Mannerheim, 1853
)
comb. n.
(
Figures 2
a, 3a, 4a, 6a, 7a, 9a–b, 10)
Hylastes subcostulatus
Mannerheim, 1853
:239
. (Kenai Peninsula, Alaska,
USA
, lost)
H. cristatus
Mannerheim, 1853
:239
(Kenai Peninsula, Alaska,
USA
, lost)
H. alternans
Chapuis, 1869
:22
(unspecified locality,
Mexico
)
Hylurgops subcostulatus
,
LeConte, 1876
:389
H. cristatus
,
LeConte, 1876
:389
H. alternans
,
Swaine, 1909
:116
Hylastes
(
Hylastes
)
cristatus
,
Hagedorn, 1910
:45
H.
(
Hylurgops
)
subcostulatus
,
Hagedorn, 1910
:46
H. subcostulatus subcostulatus
,
Wood, 1982
:91
H. subcostulatus alternans
,
Wood, 1982
:91
Diagnosis.
Distinguished from all other species in the
Hylastini
by the strongly elevated odd numbered elytral interstriae
Fig. 9
a), by the dense dorsal cover of cup-shaped setae (
Fig. 9
b), the strongly pointed anterior margin of the mesoventrite, and by the more elongate aedeagus.
Description. Size
. Length 3.1–4.7 (avg. 4.0 ± 0.4) mm long, 2.7× longer than wide.
Color
. Mature adult dorsal color brownish red, ventral sclerites dark reddish-brown.
Frons
. Mid-frontal impression deep, becoming deeper from convex area below eyes towards epistoma, surface evenly punctate, inter-puncture spaces half the width of a puncture, shiny; carina elevated, short, shiny if present, extending from below the vertical impression to epistoma; epistomal lobe narrow; vestiture consists of hair-like setae, longer below middle, length of 2–7× the diameter of a puncture.
Pronotum
. Broad, 0.9–1.0 (avg. 0.9 ± 0.3)x as long as wide, distinctly constricted anteriorly (
Fig. 9
c), widest near basal fourth, sides of basal fifth slightly elevated forming a narrow margin, sides rounded at middle, constricted on anterior fifth; dorsal median line sometimes present, if so extending anteriorly from base to fourfifths of pronotum, surface shiny, slightly raised, usually concealed by cup-shaped setae; interspaces evenly, minutely punctate, punctures separated by distance equal to ⅓ diameter of large punctures, margin smooth, shiny, and usually concealed by cup-shaped setae; additional vestiture consisting of sparse, erect bristles, 3× length of large discal punctures, longer at marginal areas.
Elytra
. Length/width ratio 1.7–1.9 (avg. 1.8 ± 0.1); anterior margin distinctly procurved, crenulate marginal line distinct and elevated; striae shallowly impressed, increasing from narrower than interstriae near base to wider at declivity, with deep, round punctures with shiny surfaces, less than their diameter apart; discal interstriae smooth, shiny, minutely punctate (seen at 100× or more), concealed by cup-shaped setae, single midline of erect bristles separated by distance of two strial punctures, rising behind interstrial granules, as long as a discal puncture diameter.
Declivity
. Convex, alternate interstriae strongly elevated (
Fig. 9
a), with large tubercles as wide or wider than rest of interstrial costa; vestiture consisting of a bristle rising behind each granule, 1–3× as long as strial puncture and a ground surface cover of dense, recumbent, cup-shaped setae.
Ventral sclerites
. Glossy, punctured.
Legs
. Tarsi dark reddish-brown; protibiae with two large socketed teeth before apical angle; meso- and metatibiae with one or two large socketed teeth before apical angle; third tarsal segment slightly broader than second.
Aedeagus
. Apodemes proportionally shorter than aedeagus in contrast to those in New World species of
Hylurgops
(
Figs. 7
b–i). Aedeagus elongate cylindrical, ventrally straight (
Fig. 6
a), barely arcuate dorsally. Without neck-like extension (
Fig. 6
c) of apodemes base (
Fig. 6
a) (
Grocholski
et al
. 1976
). Tegmen with a short manubrium.
Gallery
: The maternal gallery is longitudinal, uniramous (
Hopkins 1902
), slightly sinuate (
Fig. 3
a). Eggs are laid in only one side of the gallery from which larval galleries run perpendicular to that side only (
Cibrián-Tovar
et al
. 1995
).
Material examined.
850 specimens
from the
CNCI
,
CSUC
and the
USNM
collections were examined.
CANADA
.
British
Columbia
: Coldwater (
CNCI
), Midday Valley, Merritt (
CNCI
), Peachland (
CNCI
), Summerland (
CNCI
), Vancouver (
CNCI
).
MEXICO
.
Chiapas
:
5 mi
. E
San Cristobal
(
CNCI
),
6 mi
. SE
San Cristobal
(
CNCI
),
San Cristobal
(
CNCI
).
Chihuahua
: Mesa del Huracan (
CNCI
).
Durango
:
3 mi
. E El Salto (
CNCI
),
7 mi
. W El Salto (
CNCI
),
10 mi
. SW El Salto (
CNCI
),
10 mi
. W El Salto (
CNCI
),
11 mi
. W El Salto (
CNCI
),
11 mi
. SW El Salto (
CNCI
), Buenos Aires,
10 mi
. W La Ciudad (
CNCI
).
Mexico
City
(
CNCI
,
DEBC
).
Nuevo Leon
: Cerro Potosi (
CNCI
), NE slope Cerro Potosi, Mpio. Galaena (
CNCI
).
Puebla
:
14 mi
. W Texmelucan (
DEBC
), km 60 Rd Mexico-Puebla (
CNCI
), Zoquiapan NF (
CNCI
).
USA
.
Arizona
: Apache Co.: Brady Springs, SE Vernon, Sitgreaves NF (
UAIC
); Cochise Co.: Barfoot Grds. (
DEBC
), Barfoot picnic Grds., Chiricahua Mountains (
CNCI
,
DEBC
); Coconino Co.:
10 mi
. SW Flagstaff (
CNCI
); Graham Co.: Mount Graham (
CNCI
), Pinaleño Mountains (
CNCI
); Greenlee Co.: Hannagan Camp (
CNCI
),
15 mi
. S Alpine (
CNCI
); Pima Co.: Mount Lemmon, Sta.
Catalina Mountains
(
CNCI
), Sta.
Catalina Mountains
(
CNCI
), Bear Canyon, Chiricahua Mountains (
CNCI
); Yavapai Co.: Prescott NF, Prescott (
CNCI
).
California
: El Dorado Co.:
10 mi
. E Georgetown, Blodgett Forest,
UC
(
CNCI
),
3 mi
. E Kyburz (
CNCI
), Fallen Leaf Lake (
CNCI
,
DEBC
), Placerville (
CNCI
,
DEBC
), El Dorado NF (
CNCI
); Madera Co.: Chiquito Basin (
CNCI
); Modoc Co.: Hackamore (
DEBC
), Modoc NF (
CNCI
); Placer Co.: Big Bend Ranger Sta. (
DEBC
); San Bernardino Co.: Big Bear Lake (
CNCI
); San Diego Co. (
CNCI
).
Colorado
: Bent Co.: Las Animas Co. (
CSUC
); Chaffee Co.: CR-386 N Buena Vista (
CSUC
), Droney Gulch, Salida (
CSUC
); Douglas Co.: Franktown (
CSUC
); El Paso Co.: Black Forest (
CSUC
); La Plata Co.: Electra Lake (
CSUC
); Larimer Co.: Buckhorn Canyon (
DEBC
), Poudre Canyon (
DEBC
); Montezuma Co.: Dolores FS Rd 527 (
CSUC
), Mancos (
CSUC
); Montrose Co.: Sanborn Pk. (
CSUC
).
Idaho
: Kootenai Co.: near Coeur d' Alene (
CNCI
); Latah Co.: Deary (
CNCI
).
Montana
: Lake Co.: Pablo (
CNCI
); Ravalli Co.: Hamilton (
CNCI
).
New
Mexico
: Otero Co.: Cloudcroft (
CNCI
).
Oregon
: Josephine Co.: Oregon Caves Nat’l Monument (
CNCI
), Klamath Co.: Ft. Klamath (
CNCI
).
South Dakota
: Custer Co.: Bear Mountain area Black Hills NF (
RMRS
), Pennington Co.: Rushmore Mt. Black Hills (
CNCI
).
Utah
: Garfield Co.: Panquitch Lake, Dixie NF (
CNCI
,
DEBC
); Juab Co.: The Mammoth (
CNCI
); Ouray Co.: Long Hollow, Dixie NF (
DEBC
); Sevier Co.: Pin Hollow, Fish Lake (
CNCI
,
DEBC
).
Washington
: Walla Walla Co.: Kooskooskie (
CNCI
).
Hosts.
Picea engelmannii
,
P. pungens
,
Pinus arizonica
var.
cooperi
,
P. ayacahuite
,
P. contorta
,
P. duranguensis
,
P. engelmannii
,
P. hartwegii
,
P. jeffreyi
,
P. lambertiana
,
P. leiophylla
,
P. leiophylla var chihuahuana
,
P. montezumae
,
P. ponderosa
,
P. pseudostrobus
,
P. strobiformis
,
P. teocote
,
Pseudotsuga menziesii
, and
Tsuga heterophylla
.
Distribution
(
Fig. 10
). NORTH
AMERICA
: British
Columbia
,
Canada
to Chiapas,
Mexico
and the Black Hills of South Dakota. There is only one known record from the Kenai Peninsula of Alaska, the putative
type
locality (
Mannerheim 1853
).
Discussion.
Hylastes subcostulatus
was described by
Mannerheim (1853)
from a single specimen collected by Dr. Fredrick Frankenhaeuser from the Kenai Peninsula in Alaska as part of an early Russian expedition. Another specimen in the same collection was described as
Hylastes cristatus
by
Mannerheim (1853)
and later synonymized with
H. subcostulatus
by
Wood (1982)
.
FIGURE 10.
Distribution of
Pachysquamus subcostulatus
showing location of Mannerheim’s lost types on the Kenai Peninsula, Alaska (insert).
The lack of collection records between British
Columbia
and the Mannerheim
type
from the Kenai Peninsula is intriguing. The
type
specimens of both
H. subcostulatus
and
H. cristatus
are considered lost (
Wood 1969
,
1982
). Subsequent re-descriptions, including those of
LeConte (1868)
and Chapuis (
H. alternans
, 1869
) were made from specimens collected from British
Columbia
and
Mexico
, respectively; however, the original description by Mannerheim is adequate to identify the species. The possibility that the
type
specimen was mislabeled should be considered.
Wood (1982)
recognized
H. alternans
as a subspecies of
H. subcostulatus
based on what he considered to be a population with more elevated declivital interstriae and, in these, more inflated tubercles in specimens occurring south of central Arizona in contrast to specimens occurring north of that area. The subspecific concept has been questioned (D.E. Bright pers. comm.) based on the uninterrupted distribution of both geographical forms. Examination of specimens from throughout the species’ range suggests that the size of the tubercles and the elevation of interstriae are variable and do not correlate with the arbitrary geographical distribution of the subspecies considered by
Wood (1982)
.
Pachysquamus subcostulatus
ranges from the Canadian Cascades in southern British
Columbia
to the Sierra de Chiapas in southern
Mexico
. The Black Hills of South Dakota represent the easternmost limit of the species. Ignoring the questionable Kenai specimens, the northern distribution of
P. subcostulatus
corresponds with that of
P. ponderosa
. The species occurs from altitudes of
60–700 m
in
Canada
. In the continental
United States
, it occurs from elevations of
60–3,300 m
. Although it primarily attacks
P. ponderosa
, it occurs in other conifers in the genera
Pinus
,
Picea
,
Pseudotsuga
, and
Tsuga
. In
Mexico
, examined specimens were collected from elevations ranging from
2,300–3,700 m
.
As with other members in the
Hylastini
,
P. subcostulatus
selects and develops in conifers that have been weakened or killed by other bark beetles such as
Dendroctonus
or by other natural or anthropogenic agents such as severe drought and fires.