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Scarabaeoidea of Southern South America Links |
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Scarab Guide Links
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Tesserodoniella Vaz de Mello and Halftter
Tesserodoniella Vaz de Mello and Halftter 2006:60. |
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Tesserodoniella elguetai,
head.
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Tesserodoniella meridionalis, head. |
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Type species:
Tesserodoniella elguetai 2006. |
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Etymology.
Tesserodon, a similar genus, and -iella, small, refers to the proximity of this genus to
the Australian genus Tesserodon Hope and to its small size relative to other Chilean
Scarabaeinae. The name of this genus is feminine in gender. |
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Diagnosis.
The new genus is distinguished from all other New World Scarabaeinae by the
following combination of characters: Eyes small, feebly visible dorsally when head is
retracted (Figs. 1, 6); anterior trochantofemoral pit (as defined by Génier & Kohlmann 2003) present; elytra with wide pseudepipleuron externally to seventh discal stria;
mesosternal disc with a transverse depression; abdomen with ventrites articulated, sixth
abdominal ventrite as long as ventrites 3-5 together; pygidium with a basal transverse
sulcus. |
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Description.
Body: oval and short, size small (5.1-6.1 mm). Dorsal surface microgranulate; head
and pronotum covered by irregular, dense, conspicuous punctures. Head: as long as wide,
without visible dorsal carinae or sutures. Clypeus with two teeth separated by short Ushaped
emargination, and external lobe beside each tooth. Dorsal eye surface reduced,
triangular, or elongated. Head without occipital bead. Clypeal ventral process cariniform,
bordering clypeal emargination. Mentum anteriorly concave. Labial palpus with first
segment subcylindrical, widened medially; second segment almost spherical, slightly
longer than first; third segment short, cylindrical, narrower than others. Prothorax:
subrectangular or rhomboidal. Anterior angles acute. Laterally with ventrally directed
carina in posterior two-thirds; carina externally directed in anterior third, originating at
strong angle in lateral border, subparallel in posterior two-thirds, convergent in anterior
third. Posterior margin straight. Hypomeron with acute transverse carina, extending from
external side of procoxal cavity to anterior third of lateral pronotal carina. Hypomeral
surface concave anterior to transverse carina, flat to feebly convex posterior to transverse
carina, with longitudinal keel parallel to external margin. Elytra: Disc convex, with seven
double striae; striae with small umbilicate punctures separated by five or more diameters.
Humerus without conspicuous calli. Pseudoepipleuron with two inconspicuous striae; one
dividing pseudoepipleuron in almost equivalent halves, conspicuous only medially;
second stria juxtaposed to epipleural carina, conspicuously impressed from basal fifth to
pseudoepipleural apex. Epipleuron wide, gradually narrowed to apex, except for strongly
widened basal region. Microgranulations on elytral disk and pseudoepipleuron more
conspicuous than on remaining body parts. Hind wings reduced. Mesosternum: long,
narrowed medially. Surface covered by large, dense, ocellate punctures. Disc with evident,
transverse concavity; convex at each side of depression. Mesoepimeron trapezoidal with
strong carina parallel to anterior margin. Meso-metasternal suture straight, inconspicuous,
effaced, in obtuse angle. Metasternum: covered by large, dense ocellate punctures;
punctures larger laterally, denser, deeper, smaller on disc. Anterior lobe narrower at base
than apically, apically 4/3 as wide as basal width; with small lateral round depression at
base, depressions linked to each other by concave, inconspicuous U-shaped sulcus; sulcus
with vertex posteriorly directed. Legs: apico-anterior femoral pit present, rounded. Protibia
conspicuously curved internally, externally less curved due to apical expansion; externally
with three conspicuous teeth in apical half, median tooth closer to apical tooth. Ventral
median longitudinal carina with strong tubercle at tarsal insertion. Spur conical, narrow, as
long as tarsal segments 1-3 combined. Protarsus feebly longer than apical tibial width; segments 1-4 subequal, subcylindrical, as long as wide; tarsomere 5 as long as tarsomeres
2-4 together, laterally flattened, distally widened. Claws small, simple, falciform.
Mesofemur elongated. Mesotibia triangular with straight sides, evenly widened to apex, as
long as mesofemur. Larger mesotibial spur subconical, just shorter than mesotarsomeres
1-2 combined. Mesotarsomeres 1-4 decreasing in size towards claw; tarsomere 5 with
claw as long as tarsomeres 3-4 combined. Metafemur evenly and strongly widened at
middle, with strong posterior ventral carina; posterior margin prolonged into conspicuous
lobe in apical fourth. Metatibia long, narrow, weakly widened apically; externally serrate
in apical two thirds; apex strongly widened externally, obliquely truncate. Metatibial spur
subconical, as long as tarsomeres 1-2 combined. Metatarsi similar to that of middle legs.
Abdomen with ventrites 2-4 of equal length, ventrite 5 one third the length of ventrite 4;
ventrite 6 as long as 3-5 combined, not narrowed medially. Pygidium almost twice as wide
as long; disc strongly convex with ocellate punctures medially; bordered complete, with
strong basal sulcus. Male genitalia with asymmetric parameres, left paramere (in dorsal
view) longer and wider at apex. |
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Sexual dimorphism.
Male protibia with strong internal apical tooth directed foreward and downward,
external teeth narrower than in females; male metatibiae with larger external serrations;
and male abdominal ventrite 5 narrowed medially (width even in females). |
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Remarks.
The new genus is readily distinguishable from other New World canthonine genera.
The genus is quite similar to two Australian genera: Tesserodon Hope and Aptenocanthon
Matthews. These three genera are all characterized by the presence of the anterior
trochantofemoral pit and the position and form of the pseudoepipleuron. Based on our
study of dung beetle genera, we predict that these characters are phylogenetically
informative and that the three genera form a clade. The three genera may be related,
although more distantly, to the South American genera Zonocopris Arrow, Cryptocanthon Balthasar, Paracryptocanthon Howden & Cook, as well as the New Zealand genus
Saphobius Broun, because they all share the trochantofemoral pit structure. However,
Zonocopris, Cryptocanthon, Paracryptocanthon, and Saphobius all have a somewhat
distinct pseudoepipleuron. Tesserodoniella differs from both Australian genera in the form
of the prothorax, elytral striae, and in having the first metatarsomere slightly larger than
the second. |
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Excerpt from:
Vaz de Mello, F. Z., G. Halffter. 2006. A new dung beetle genus with two new species from Chile
(Coleoptera: Scarabaeidae: Scarabaeinae). Zootaxa 1193: 59–68 |
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