Scaphodius CHAPUIS 1874
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publication ID |
https://doi.org/ 10.5281/zenodo.5276273 |
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persistent identifier |
https://treatment.plazi.org/id/7425174F-FFE9-F749-FFD9-1091A972FD4C |
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treatment provided by |
Carolina |
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scientific name |
Scaphodius CHAPUIS 1874 |
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= Nyetra BALY 1877 syn.nov.
T y p e s p e c i e s Scaphodius comptus CHAPUIS 1874, by monotypy.
D i a g n o s i s A genus of Cryptocephalinae , Cryptocephalini, Monachulina . Eyes convex, small, curvature even, no canthus; antennal segments 7-11 usually broadest; anterior and lateral sides of pronotum distinctly bordered, basal margin unbordered, i. e. toothed, base of pronotum triangularly extended at middle, notched to receive scutellum; prosternal process quadrate to transverse rectangular, with or without a pair of acute projections; scutellum plain, small, flat, fusiform, i.e. spindle-shaped; elytral puncturation, colour, and surface sculpture variable, dorsally glabrous or setose; tarsi elongate; claws toothed, kotpresse with one ventral and two dorsal sclerites, spermatheca hookshaped.
H a b i t u s: ( Figs 44-52 View Figs 44-48 View Figs 49-52 ). Size 2.4-6.4 mm; body short cylindrical, elytra slightly narrowed apically, pronotum plain to strongly vaulted; colour entirely yellowish, or reddishbrown to rust red, or black, with or without yellow markings; dorsum glabrous or setose.
H e a d. ( Figs 24-32 View Figs 24-32 ) Large, hypognathous, sunk into thorax, puncturation coarse, sometimes with wrinkles, eyes evenly convex, small, distant; no canthus, inner margin of eye at most arcuate ( Figs 24, 28 View Figs 24-32 ); antennae inserted low on frons, without grooves between them, antennae with all segments elongate, scape very long, pedicel shortest, and 6-11 usually broadest, setae present on all antennomeres, dense on sixth to eleventh, antennal length 0.45 to 0.60 body length, antennae relatively longer in males, antennal basiconic sensilla in circular pits at apices of segments, interantennal space 3.5 times diameter of antennal socket, below antennal socket with a shallow groove to receive antenna; clypeal area not delimited, i.e. frontoclypeal suture weak to reduced, clypeus basally straight to convex in female, slightly to strongly modified in male, glabrous; gena short, lobate at apex, labrum transverse to quadrate; last maxillary and labial palps narrowing apically, concave, apical segment of labial palp shaped as maxillary palp; mandible robust, with two large teeth, male usually with slightly to strongly enlarged mandibles.
T h o r a x. Prothorax: pronotum straight to evenly curved at sides and contracted at apex, pronotum broadest at base, approximately two times wider than long and anteriorly half as wide as basally, with or without lateral transverse impressions, in lateral view pronotum plain to humped; apical and lateral sides bordered, lateral margins even, carinate, anterior margin semi-circular, basal margin unbordered, i. e. toothed, posterior lobe of pronotum narrow, triangular, notched to receive scutellum; puncturation on disc shallow to coarse, or with longitudinal furrows, hind corners with setiferous pore, front edge of pronotum ridged, sides of front margin not projecting beyond prosternum, posterior angles of pronotum triangularly produced, male pronotum as wide as or slightly wider than elytral base; intercoxal prosternal process wide, quadrate to transverse i.e. approximately two times wider than long, wider than coxal cavity, with more or less coarse punctures, front margin convex or concave, with a narrow carina, plain or slightly bend downwards, hind margin simple, or bearing a pair of flat acute or blunt rounded posterolateral projections between coxae, slightly convex, straight or deeply concave, prosternal opening relatively narrow, posterior margin of prosternal process does not extend beyond hypomeral projection, coxal cavity closed, prosternal process densely setose, hypomeron impunctate, but irregularly wrinkled; proendosternites about as long as prosternal process, their base long and ca. 0.5 times width of apex; procoxal cavity wider than long; mesothorax: scutellum small, flat, rombiform, i.e. spindle-shaped, impunctate, smooth or with fine punctures; mesoscutum nearly twice as long as mesoscutellum, medially with coarse puncturation, keeled on midline, anteriorly angulate with narrow, elongate arms, without lateral patches of microchaetae; mesosternum distinct between coxae, broad, mesosternal intercoxal process as wide as prosternal process, elytra 2-3 X length of pronotum, slightly apically expanded for basal ¼ then gradually attenuate, with nine rows of punctures or non-punctured regular striae, plus a short scutellar stria or puncture row and a stria or row of punctures abutting epipleura, at least outer interstriae convex, or puncturation substriate or confused, basal margin of elytra simple, elytra with prominent humeri, elytra without lateral transverse impressions, in some species elytra with ridges or tubercles, elytra regularly oblate or apically truncate, reaching base of pygidium, elytral suture bordered, not toothed; epipleuron strongly bend inwards, short, abruptly narrowing, reaching anterior to apical margin of first abdominal sternite only, smooth or irregularly punctured; metathorax: hind wing transparent or apically dark, radial triangle cell closed, small to moderately in size, radial transverse short, radio-mediane absent, i.e. medial cell open, median veins poorly sclerotized, cubital nerves normally developed, 1 st cubital nerve small to simple, 1 st anal nerve and median nerves 1 and 2 strongly developed, 2 nd anal nerve reduced, 3 rd anal nerve normal to enlarged, two cubito-anal cells present; metasternum even, not prominent and convexly swollen ventrally, epimeron densely covered with short white adpressed setae; legs ( Fig. 49 View Figs 49-52 ) strong and relatively short, all femora of similar size, or hind femora slightly larger, without ventral keel, tibiae almost straight, tibial spurs absent, external edge of tibia not or only slightly excavate, excavation with or without fringe of strong setae, tarsal segments subquadrate to elongate, in male first segment of fore- and mid tarsi widened in some species, but still elongate, tarsomeres dorsally convex, claws relatively small, symmetrical, dentate to appendiculate.
A b d o m e n.Tergiteshard,strongly sclerotised, spiracles free in basal tergites; lateral lobe at base of abdomen large, rectangular, intercoxal abdominal process of sternite III broad, straight to slightly concave, sternite III slightly shorter or as long as sternites IV to VII along midline; sternite VII not indented in male, apex of male abdomen without or with a shallow hollow; tergites reaching sternites; pygidium densely microsculptured, dull, regularly convex, sometimes with a bulging carina along midline.
M a l e g e n i t a l i a. ( Figs 1-19 View Figs 1-13 View Figs 14-23 ) Aedeagus straight, aedeagal lobe with a specific tip, venter simple, without longitudinal ventral keel or transparent "windows" in wall of reflexed apex, ventral and dorsal aedeagal setae present, basal 1/3 to 1/2 of ostium covered by a large endosclerite, in some species additional endosclerites visible; tegmen broad, U- or V-shaped, keeled, with expanded sides and bifid base, spiculum gastrale fused.
F e m a l e g e n i t a l i a a n d K o t p r e s s e. ( Figs 33-43 View Figs 33-43 ) Vaginal palp with lateral and basal borders sclerotized, apical border not sclerotized, rounded ( Fig. 43 View Figs 33-43 ); spermatheca hook-shaped, pump relatively narrow, as long as or shorter than receptacle, spermathecal ductus straight, i.e. not spiral, long, sometimes ball-like coiled up ( Figs 39- 42 View Figs 33-43 ), accessory gland simply emerging from a little stick; rectum with dorsal fold of intestine and lateral folds, kotpresse with two dorsal and one ventral sclerites; dorsal sclerites straight ( Figs 33, 35 View Figs 33-43 ), rarely extended towards dorsal fold ( Fig. 38 View Figs 33-43 ), ventrally bend part of dorsal sclerite absent, apodemes slightly wider than the rectum, dorsal sclerotisation of the lateral fold present ( Figs 33, 35, 38 View Figs 33-43 ); ventral sclerite is a crosswise band, ending in apodemes, that are large and wider than the rectum ( Figs 34, 36, 37 View Figs 33-43 ), rarely additionally with pigmented chitinpolster ( Fig. 37 View Figs 33-43 ); females with large deep egg-hollow, apex not indented.
I m m a t u r e s t a g e s. Unknown, the egg of one yet undescribed species from Mt. Panie with long spines on the faecal plates.
D i f f e r e n t i a l d i a g n o s i s. Scaphodius may be distinguished from Coenobius SUFFRIAN 1857 and Aprionota MAULIK 1929 by the basiconic sensillae located in circular pits at the apices of the antennomeres, and the hook-like spermatheca. Scaphodius differs from Ditropidella REID 1998 by setae on the mandibles, punctate gena, clypeal area not delimited and the absence of a canthus. Scaphodius is very similar to Ditropidus , especially some species described in Elaphodes. The only difference I noticed among the species available for my study are the eyes being not emarginate, i.e. without deep canthus, but this has to be verified in other species as the genus Ditropidus has more than 200 species.
D i s t r i b u t i o n. The genus is endemic to New Caledonia.
N o t e. The genus Nyetra was described by monotypy. The generic type species Nyetra forcipata is re-described below. Baly (1877) first mentioned the prolongation of the male mouth-parts and clypeus being remarkable. In this study, it was shown that this sexual dimorphism can also be found in Scaphodius striaticollis and that intermediate forms exist from absence of dimorphism to very strong dimorphism ( Figs 24-32 View Figs 24-32 ). BALY (1877) proposed the shape of the hind margin of the prothorax to be a suitable character to distinguish Scaphodius from Nyetra, with the margin being straight in Scaphodius and concave in Nyetra. As figured in Figs 53-58 View Figs 53-58 , the apical margin of the prosternal process is straigth in S. striaticollis and deeply concave in S. amieus nov.sp., there are several intermediate forms, and it is even convex in S. complanatus nov.sp. The shape of the prothorax was rated to be an important character to distinguish genera by SUFFRIAN (1859), but this cannot be confirmed in the group under study.
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