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CANADIAN
ENTOMOLOGIST
589
FIGS.9-12. 9,
10 T r a c h y c r u s u s s t r i a t u l u s
sp.nov.: 9, head and p ronotum; 10, lef t middle t ibia .
11, 12,
carabatermes amazonensis
Howden:
I
dorsum; 12, head and pronotum.
third; surface sculpture similar to head; pronotal edges thin, lacking distinct marginal bead,
laterally with marginal row of seta-bearing punctures, anterior and posterior angles not
indicated. Scutellum about two-thirds as long as wide, basal half tumid on each side of feebly
depressed midline, apical half or less feebly concave; surface with several widely separated,
small punctures, otherwise smooth and shining; sides inwardly arcuate or straight, apex
acute. Elytra Fig. 2 with striae feebly impressed, intervals with elongate-oval reticulations
or polygons, otherwise shining and with scattered, long flying hairs; elytra lacking posterior
tubercles or carinae, posterior declivous portions attenuate, slightly explanate near acutely
rounded apices. Metathoracic wings Fig.
7)
fully developed. Pygidium with v-shaped
median membranous area widest basally, terminating in acute point above apex of pygidium.
Antenna nine-segmented sixth segment often appearing divided making antenna appear
10-segmented),club Fig.
4)
three-segmented, club segments elongate. Mandible thin, sharp
and narrow apically, scarcely visible beyond labrum. Mentum Fig.
3)
flat, broad; apically
truncate or very widely, shallowly emarginate. Maxillary palpus four-segmented, apical
segment enlarged, widest near middle, then tapered to acutely rounded apex. Labial palpus
small, three-segmented, apical segment slender, as long as basal segments combined. Fore
coxae Fig.
3)
narrowly separated, very elongate-conical, bases transverse. Fore femur with
small patch of setae on anterior base adjacent to coxa, row of scattered long setae present
along ventral edge. Fore tibia with apical and one proximal tooth, outer edge with row of
stout setae, setal bases making edge feebly serrate; males with unusually flattened and
hooked apical spur Fig. 5); females with apical spur slender, straight, tip acute. Fore tarsus
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590 THE C N DI N
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with basal and apical segments twice as long as wide, other segments as long as wide or
longer; tarsus attached near apical fourth on ventral surface of tibia. Middle and hind coxae
very narrowly separated; middle and hind tibiae flattened, outer surface with rows of erect
setae, setal bases tuberculate, surface between tubercles finely reticulate or imbricate.
Metasternurn short, length along midline about one-fourth width. Abdomen (of dried
specimens) shrunken, with membranous areas between tergites and sternites (abdomen
seemingly capable of considerable expansion).
Type Species
rachycrusus lescheni
sp.nov.
Remarks
The genus rachycrusus can be distinguished from other New World genera of
Ceratocanthinae by the following combination of characters: clypeal margin scalloped;
surface of head and pronotum with polygonal reticulations and long, erect setae; eytral apices
slightly extended, acutely rounded; outer flattened surface of middle and hind tibiae lacking
distinct carinae, with rows of scattered long, erect setae, each arising from a tuberculate base;
males with fore tibial spur flattened and with a distinct hook on the end (Fig. 5).
The two species here placed in this genus are capable of flexing the head and pronotum
downward, forming an elongate ball as is typical for many Ceratocanthinae.
rachycrusus lescheni sp nov
(Figs. 1-8)
Holotype Male, length 4.9 mm (combined length of head, pronotum, and elytra measured
individually), greatest width 2.0 mm. Clypeal edge with seven notches, each notch with long,
straight seta, each lobe between notches about four times as wide as notch. Edge of each
gena with four feebly indicated setose notches. Pronotum (Fig.
1)
with distinct transverse
depression in posterior median third with distinctly tumid area near posterior margin; lateral
margin on each side evenly, broadly arcuate, anterior and posterior angles not indicated. Each
elytron (Fig. 2) over twice as long as wide; striae present but obscured by transverse lines,
surface thus appearing covered with elongate reticulations; sutural and alternate intervals
with widely separated, long, erect setae (flying hairs); elytron laterally with carinate edge
delimiting narrow epipleuron, otherwise carina(e) lacking. Outer flattened surface of hind
tibia (Fig. 6) with length to width ratio of 7.5:2.2; vague carinate line present on basal half
near inner edge. Male genitalia (Fig. 8) with slightly asymmetrical parameres.
Allotype Female, length 4.6 mm (combined measurements as in male), greatest width
2.1 mm. Differing from male as follows: clypeal edge with nine notches; pronotum with
lateral edges slightly more widely rounded; fore tibial spur slender, straight, unmodified.
Other external characters not differing noticeably from male.
Type Material
Holotype, male, Peru, Dept. Loreto, Campamento San Jacinto 2 18.7SfS,
75 51.77'W, 7 July 1993,175-215 m, Richard Leschen, #42, ex: flt. icpt. trap, Qd 21 (Snow
Entomological Museum, University of Kansas). Allotype, female, same data as holotype
except #45, Qd 20 (Snow Entomological Museum, University of Kansas).
Paratypes, 3 males, 3 females. All same data as holotype except: 2,5.VII.1993, #33
Qd 20; 1,9.VII.1993, #65, Qd 21; 3,11.VI1.1993, #82, #85. Paratypes are in the Gill,
Howden, Snow Entomological Museum, and Canadian Museum of Nature collections.
Remarks
Variation in the small series is negligible. Length varies by about 0.2 mm and
width by 0.1 mm. The position and number of dorsal setae show some variation, but this
seems to be due to abrasion. The size of this species will distinguish it from its congener
described subsequently.
The species is named for Richard Leschen who not only collected the species but
recognized that it represented an undescribed taxon.
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THE CANADIAN
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591
rachycrusus striatulus sp nov
(Figs. 9, 10)
Holotype
Male, length 4.0 mm (combined measurements of head, pronotum, and elytra
measured individually), greatest width 1.8 mm. Clypeal edge with 10 notches, each with
long, straight seta, resulting scalloping with each lobe about three times as wide as notch.
Edge of each gena with five or six feebly indented setose notches. Pronotum (Fig. 9) with
shallow median depression in posterior half, lateral thirds of pronotum each with shallow
depression midway between broadly rounded margins; lateral margin on each side evenly,
broadly arcuate, anterior and posterior angles not indicated. Each elytron slightly more than
twice as long as wide, striae on disc represented by feebly impressed lines, striae becoming
obsolete laterally and just posterior to basal edge of elytron, intervals medially with scattered
flying hairs and row of obscure reticulations; elytron laterally in basal two-thirds with
rounded ridge above and paralleling epipleural carina; otherwise lacking distinct carinae.
Outer flattened surface of hind tibia (Fig. 10) twice as long as wide, ratio of 2: l; vague
carinate line present on basal half near inner edge. [Genitalia not extracted.]
Allotype
Female, length 3.6 mm (combined measurements), greatest width 1.7 mm. Dif-
fering from male as follows: median posterior pronotal depression smaller, less pronounced;
striae on elytral disc slightly more impressed; fore tibia1 spur slender, straight, unmodified.
Other external characters not differing noticeably from male.
Type M aterial
Holotype, male, Peru, Dept. Loreto, Teniente Lopez, 2 35.66'S, 76 06.92'W,
23 July 1993, 210-240 m, Richard Leschen #191, ex flight intercept trap (Snow Entomo-
logical Museum, University of Kansas). Allotype, female, same data as holotype except
1.5
km
N. Teniente Lopez, 22.VII.1993, #165, Qd 17 (Howden).
Remarks Although T. striatulus is closely related to T. lescheni, T. striatulus can be distin-
guished by its smaller size, shallower median depression of the pronotum, less reticulate
elytra, and distinctly broader middle and hind tibiae.
Relationships
In the paper describing Xenocanthus Howden and Gill (1988a), we listed 20 characters
and their character states (1988a, p. 2075, table 1) that we felt were useful in placing odd
genera in either the Ceratocanthinae or in related subfamilies. Within the Ceratocanthinae
we found that Ceratocanthus White, Germarostes Paulian, Scarabaeinus Silvestri (Howden,
1971), Scarabatermes Howden, and Xenocanthus all shared the following apomorphies
(character numbers are those used in tables 1 and
2
in Howden and Gill 1988a, p. 2075):
5, eye canthus dividing half or more of eye; 7, antenna1 club elongate; 10, prosternum
lacking keels or spines, capable of flexing downward; 12, metastemum short between middle
and hind coxae; 13, anterior tarsal insertion on underside of tibia near apical fourth;
16, M-Cu loop of metathoracic wing absent. Subsequently another unusually modified
genus, Ivieolus Howden and Gill (1988b), was found to share all of the above apomorphies.
Trachycrusus is also apomorphic for characters 5, 7, 10, 12,
13
and 16 (as well as for
characters 1 ,8, and 15). Although these character states indicate that Trachycrusus belongs
in the Ceratocanthinae, they do not reveal any information about relationships within the
subfamily. Table 1 lists some additional characters that help elucidate the relationship of
Trachycrusus to other genera in the Ceratocanthinae. For polarizing these character states,
we have used the hybosorine genera Liparochrus Erichson and Phaeochrous Castelnau as
the outgroup (Howden and Gill 1 988~) .he results are presented in Table 2.
A
number of other characters could be listed, but as far as we can ascertain they would
not improve our assessment of the placement of Trachycrusus. Our analysis indicates that
Trachycrusus is most closely related to Scarabatermes (Figs. 11, 12), sharing five of seven
apomorphies (Table 2). However, it also shares the apomorphic state of flattened middle and
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THE CANAD IAN ENTOMOLOGIST July/August
995
TABLE
. Plesiomorphic and apomorphic states of additional characters useful in assessing phylogenetic
relationships among ceratocanthine genera. Supplement to list provided by Howden and Gill
1 9 8 8 ~ ) .
haracter
and state numbers follow the sequence in Howden and Gill
1 9 8 8 ~ )
Character Plesiomorphic
-)
Apomorphic
+)
2 Anterior clypeal edge
22
Anterior pronotal angles
23 Pronotal disc
4 Elytral carinae in addition
to epipleural carina
25 Elytral setae
26 Apex of elytron
27 Middle and hind tibiae
Even Scalloped
Abruptly rounded, acute
Evenly rounded, angle absent
Evenly convex
Uneven or with indentations
Absent Present, either laterally or
apically or both
Short or absent
Long, erect flying hairs)
Rounded Attenuate, slightly reflexed
Round or oval in cross
Flattened
section
hind tibiae characteristic of typical ceratocanthines such as Astaenomoechus Martinez and
Pereira and Ceratocanthus. As a result, Trachycrusus bridges the gap between the highly
modified South American genera and the more typical ceratocanthines.
It should be emphasized that some Old World genera that we have not examined may
actually be more closely related to Trachycrusus than either Scarabatermes or Astaeno-
moechus,
because
Trachycrusus
has several autapomorphies that, if they occur elsewhere,
might change our placement. At present, however, both the wide non-emarginate mentum
and the peculiar anterior tarsal spur of the male are unique to Trachycrusus.
The other reason for our tentative analysis is our conviction that further collecting with
flight interception traps in tropical South America will almost certainly produce many
additional undescribed Ceratocanthinae.
Acknowledgments
We are very much indebted to
R
Leschen and J.S. Ashe, Department of Entomology,
University of Kansas, Lawrence, for furnishing us the specimens used in this study. We also
thank F. GCnier, Canadian Museum of Nature, Ottawa, for his assistance with this project.
The SEM micrographs were done by L.E.C. Ling, Carleton University, and
K
McLachlan-
Hamilton and
T.
MacKechnie assisted with the plates and manuscript. This work has been
supported, in part, by an operating grant to H.F. Howden from the Natural Sciences and
Engineering Research Council of Canada.
TABLE
Distribution of character states listed in Table
1
among selected ceratocanthine
genera. ( + indicates apomorphic condition)
Character state
Genus
2
23 4
25 26 27
Astaenomoechus
Ceratocanthus
Germarostes
Ivieolus
Scarabaeinus
Scarabatermes
Trachycrusus
Xenocanthus
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References
Howden, H.F. 1971. Five unusual genera of New World Scarabaeidae (Coleoptera).The Canadian Entomologist
103: 1463-1471.
1973.
Scarabatermes amazonensis,
anew genus, new species, of termitophilous Scarabaeidae Coleoptera).
The Canadian Entomologist 105: 29-33.
Howden, H.F., and B.D. Gill. 1988a. Xenocanthus, a new genus of inquiline Scarabaeidae from southeastern
Venezuela (Coleoptera). Canadian Journal of Zoology
:
2071-2076.
1988b. A fourth genus of unusually modified Ceratocanthinae (Coleoptera: Scarabaeidae) from South
America.
Canadian Journal of Zoology :
2077-2079.
Paulian,
R
1982. Revision des Ckratocanthides (Coleoptera Scarabaeoidea) d Am6rique du Sud. Mimoires du
Musium national Histoire naturelle, Sirie A Zoologie 24:
110 pp. plates I XVIII.
(Date received: 17 April 1994; date accepted: April 1995)
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