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Scarabaeoidea of Southern South America Links |
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Scarab Guide Links
(goes to the University of Nebraska
web site) |
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Classification |
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Arctodium Burmeister, 1844
Arctodium Dejean 1833: 167 (nomen nudum).
Cratoscelis Erichson 1835: 267 (synonym).
Arctodium Burmeister 1844: 9 (valid name). |
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Arctodium vulpinum (Erichson).
Illustration by Dan Schmidt. |
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Map of central Chile showing distribution of Arctodium discolor
and A. planum |
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Map of central Chile showing distribution of Arctodium vulpinum
and A. mahdii. |
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Type species:
Cratoscelis vulpina Erichson, 1835 by subsequent designation (Chapin 1938). |
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Etymology. The name Arctodium likely comes from the Latin word arctos, meaning bear or bearlike
(Brown 1956). The gender is neuter. |
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Description. Male. Length 4.5-12.5 mm; width 3.0-8.0 mm. Color: Head, pronotum, and scutellum
black; venter, elytra, legs, pygidium, and setae variable. Head: Head strongly deflexed.
Frons slightly concave. Surface setosely punctate; punctures and setae variable. Labrum
clearly visible in dorsal view, exposed part in dorsal view 2/3 as long as clypeus.
Mandibles protruding anteriorly beyond labrum; apices with 2 apical teeth, strongly
reflexed. Maxilla with moderately long galea, galea 1/2 to subequal
in length to head (including mouthparts), setose; setae curved, short, dense, forming row,
pale yellow to light tan. Maxillary palpi 4-segmented; segment 1 small, 1/2 length of 2,
2-3 cylindrical, equal in length, 4 fusiform. Labium deeply grooved longitudinally. Labial
palpi 3-segmented: segments 1-2 conical, 3 fusiform. Eye completely divided into dorsal
and ventral sections by canthus. Antenna 9-segmented. Pronotum: Surface setosely
punctate, punctures and setae variable. Disc with weak, median, longitudinal groove.
Lateral margins with poorly developed bead. Posterior margin strongly projected
posteriorly at middle. Elytron: Length short, not covering pygidium. Propygidium: Surface
exposed, covered with long, dense, white setae; setae overlaying basal 1/5 of pygidium
(covered by elytra in some specimens), apices of setae forming straight row. Pygidium:
Lateral and apical margin with bead. Apex rounded. Venter: Abdomen with 7 exposed
segments; segments setosely punctate, punctures and setae variable. Pleural membrane
with 6 spiracles. Tergite with 1 spiracle. Legs: Surface setosely punctate; punctures and
setae variable. Protarsomere 1 3/4 length of 2, 2 long, subequal in length to 5, 3-4 short,
sub-globose, subequal in length to each other; 5 twice as long as 4. Metatibial apex with 2
spurs and 1 spine; spine between 2 spurs, long, attenuate, with sharp point at apex. Mesotarsomere and metatarsomere 1 longer than 2-4, 2-4 subequal to each other, 5
subequal to 2-4. Tarsal claws simple. Unguitractor plate with sides parallel, with 2 apical
setae. Parameres: Figs. 9c.
Female. Females differ from males in the following respects: length 5.0-12.0 mm;
width 3.0-6.5 mm. Legs: Metatibial apex with 1 spine; spine short, broadly attenuate, with
blunt point at apex. |
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Diagnosis. Arctodium is differentiated from Lichnia by the shorter galea in Arctodium that is less
than half the length of the entire body. In Lichnia the galea is more elongated
and extends at least half the length of the entire body. Also, the mandible of
Arctodium is toothed, whereas the mandible of Lichnia is smooth and rounded. The distribution range for Arctodium (see maps) extends further south than
that of Lichnia. |
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Distribution. Species of Arctodium are found in central Chile from Region V (Valparaíso) to Region
IX (La Araucania) (see maps). |
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Remarks.
According to Chapin (1938), Arctodium Burmeister should replace Cratoscelis
Erichson as the valid name of the genus. However, subsequent authors still incorrectly
used Cratoscelis as the valid name. I agree with Chapin that Cratoscelis Erichson is not a
valid name, because Lucas (1834) previously used the name Cratoscelis in connection
with a plate of figures, including the spider species Cratoscelis rufipes Lucas and
Cratoscelis nigripes Lucas (Araneae: Sicariidae). There is no description of these species,
but the International Code of Zoological Nomenclature states (Article 12.1) that for a
genus name published before 1931 to be valid, the publication must include a description,
a definition, or an indication of the taxon (International Commission on Zoological
Nomenclature 1999). Furthermore, the Code states (Article 12.2.7) that the publication of
a genus name in conjunction with an illustration is sufficient as an indication. Therefore
Cratoscelis Erichson, 1835 is a junior homonym of Cratoscelis Lucas, 1834, and
Arctodium Burmeister should be the valid name.
Arctodium was proposed by Dejean (1833) in his catalog with A. villosum Dejean as
the only species. However, there was no description, definition, or indication of A.
villosum, and therefore the name Arctodium Dejean is a nomen nudum according to Article 12 of the Code (International Commission on Zoological Nomenclature 1999). It was
Burmeister (1844) who first used the name as an invalid synonym of Cratoscelis Erichson
in association with described species (A. discolor and A. vulpina), and it is to Burmeister
(1844) that we attribute the name under Article 11.6.1 of the Code (International
Commission on Zoological Nomenclature 1999).
Dorsal view of labrum and mandibles showing form of the mandibles (a) dentate,
Arctodium vulpinum or (b) rounded, Lichnia limbata.
Arctodium discolor (Erichson, 1835). |
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Excerpt from:
Hawkins, S. J. 2006. A revision of the Chilean tribe Lichniini Burmeister, 1844
(Coleoptera: Scarabaeidae: Melolonthinae). Zootoaxa 1266:1-63. |
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