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Scarabaeoidea of Southern South America Links |
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Scarab Guide Links
(goes to the University of Nebraska
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Classification |
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Brachysternus angustus (Philippi and Philippi,1864)
Aulacopalpus angustus Philippi and Philippi 1864:322. |
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Figure 28a-c. Form of the male genitalia in Brachysternus angustus (lateral view of
parameres and apex of phallobase, caudal view of parameres, and ventral view of ventral
and lateral sclerites). |
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Map showing the distribution of B. angustus. |
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Description. Length: 15.8-20.3 mm. Width: 7.2-9.7 mm at base of elytra. Color:
Dorsally light to dark shiny apple green (occasionally bluish-green or tan), elytral margins
metallic brassy-green, apical umbone metallic green; apex of clypeus and pronotal
margin tan or green; femora, tibiae, and sternites testaceous with metallic green sheen
(occasionally entirely testaceous); pygidium metallic dark green (occasionally entirely
testaceous); propygidium and tergites castaneous. Head: Clypeal apex rectangular with
broadly rounded corners, not constricted at base; margins and apex weakly reflexed
(male) or flat (female). Frons densely punctate; punctures moderately large (0.07-0.12
mm), some setose; setae hair-like laterally and at base (sparse, short to moderately long,
tawny) and scale-like posterior to eye (dense, short, white). Clypeus confluently punctate
to rugopunctate, punctures moderate. Interocular width 3.5-6.0 transverse eye diameters.
Terminal segment of maxillary palpus (dorsally) with moderately impressed groove from
base to near apical third, segment subequal in length to segments 2-3. Antennal club
subequal in length to segments 1-7 (male) or segments 2-7 (female). Pronotum: Surface
with weakly impressed, median, longitudinal groove; disc confluently punctate, margins
confluently punctate or rugopunctate; punctures moderate in size, some setose; setae hairlike,
short to moderately long, tawny, moderately or sparsely dense. Basal bead complete
to just beyond posteriolateral angle. Elytron: Surface with 5 weakly impressed, poorly
defined, punctate, longitudinal striae between suture and humerus; punctures moderate
and small, sparse (disc), moderately dense (base), or dense (margin at apex), some setose;
setae hair-like (short to moderately long, sparse, tawny) or thickened (moderately long,
sparse, white). Intervals with similar sculpturing. Humeral and apical umbone well-developed.
Epipleuron flat, not expanded, marginal bead present; region from metacoxa to
apex setose; setae thickened, short and moderately long, dense, white. Sutural angle
square. Propygidium: Posterior margin with fringe of setae; setae thickened, short, white.
Supraspiracular ridge well-defined. Pygidium: Male: disc and middle apex with hair-like
setae (moderately long and long, moderately dense, tawny) and punctures (small, sparse);
margins with scale-like setae (dense, white). Female: disc weakly bituberculate, punctate
at margins and at middle apex; punctures moderate in size, setose; setae on disc hairlike,
tawny, moderately long and long, sparse (at margins) or moderately dense (at middle
apex), margins with scale-like setae (dense, white). Venter: Setose; male clothed with
dense, white, scale-like setae; female with sparse (disc) and dense (lateral margins), white, scale-like setae. Prosternal keel broadly triangular; apex projecting anteriorly at
about 458 with respect to ventral plane; apex produced to about level of protrochanter,
blunt. Mesometasternum with apex rounded, not produced. Apex of terminal sternite in
female deeply emarginated at middle. Legs: Larger pro- and mesotarsal claw
of male weakly bifurcate at apex. Pro- and mesotarsomere 5 of male with well developed
ventromedial tooth, apex rounded or quadrate (not acute). Metatibia with inner and outer edges straight, with 2 weak carinae; 1 at middle (poorly developed),
1 in apical third (moderately developed), carinae more developed in females;
apical 1/5 weakly divergent (more so in females). |
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Diagnosis. Brachysternus angustus is separated from other species of
Brachysternus by the well-developed humeral and apical umbones on the elytron,
the form of the male genitalia (ventral and lateral sclerites and form of
the parameres in lateral view), and the form of the pygidium in the female
(surface of disc weakly bituberculate). The species is most similar to B. spectabilis,
but differs by the green coloration on the meso- and metafemora (castaneous
or castaneous with weak green reflections in B. spectabilis); the dense,
scale-like setae on the sternites (moderately dense, thickened setae in B. spectabilis);
and the scale-like setae posterior to the eye (setae thickened in B.
spectabilis).
Brachysternus angustus bears an overall similarity to Hylamorpha elegans
(Burmeister) based on the well-developed humeral and apical umbones, distribution
of scale-like setae on the venter and pygidium, and overall coloration.
These taxa differ by several features including: larger claw split (simple in
Hylamorpha), female with apex of the last sternite emarginate (simple
in Hylamorpha), form of the male genitalia (Fig. 28), and bisetose unguitractor
plate (trisetose in Hylamorpha). |
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Distribution (see map). Recorded from 100-1,800 m elevation from O’Higgins
to Llanquihue, Chile and east to Neuquén, Argentina. |
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Locality Data. 85 specimens examined from AMNH, BCRC, CASC,
CMNC, CMNH, FMNH, GASC, LACM, MGFT, MNNC, PVGH, SEMC,
USNM, VMDM.
ARGENTINA (6). NEUQUEN (6): Lago Lácar, Parque Nacional Lanín,
Tromen. CHILE (78). BIO-BIO (1): Cerro Pemehue. CAUTIN (7): Volcán Villarrica.
CURICO´ (1): Las Trancas. LLANQUIHUE (5): Hornohuinco (11 km SW Lago
Chapo), Los Muermos (12 km S). MALLECO (38): Lonquimay, Malalcahuello,
Manzanar, Manzanar (9.2 km E), Parque Nacional Nahuelbuta, Río Chanchuco,
Villa Portales (15 km W). NUBLE (10): Las Trancas (72 km SE Chillán), Los Lleuques, Nevados de Chillán, Shangrila (SW side Volcán Chillán).
O’HIGGINS (1): Las Cabras. OSORNO (2): Parque Nacional Puyehue. VALDIVIA
(13): Lago Pirehueico, Las Lajas (W La Unión), Pirihueico, Valdivia.
NO DATA (1). |
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Temporal Data. January (9), February (10), March (1), November (17),
December (41). |
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Natural History. Brachysternus angustus has been collected in Nothofagus forests (including Nothofagus swamp and a mixed forest with Nothofagus pumilio Krasser, Araucaria araucana [C. Koch], and Chusquea species). Specimens
were collected at ultraviolet lights at night, at flight intercept traps, and
under logs. |
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Remarks. Philippi and Philippi (1864) described B. angustus based on one
male specimen. They were dubious about the generic placement of the taxon and referred to the species as
"Aulacopalpus? angustus." Based on the characters
that seemed to be indicative of the prevailing generic concepts of
Brachysternus and Aulacopalpus (claws, mesosternum, femora), Philippi and
Philippi placed the taxon in the genus Aulacopalpus. However, they queried
the reader, ". . . wouldn’t it be most sensible to combine Brachysternus and
Aulacopalpus again?" This comment reflected the confused state of the
brachysternine generic concepts at that time. |
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Excerpt from:
Jameson, M. L. and A. B. T. Smith. 2002. Revision of the South American genus Brachysternus Guérin-Ménville (Coleoptera: Ruteliinae: Anoplognathini: Brachysternina). Coleopterists Bulletin 56: 321-366. |
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