Pseudosynarmostes, Ballerio, 2008

Ballerio, Alberto, 2008, Descriptions of two new endemic genera and four new species of Ceratocanthinae (Insecta, Coleoptera, Scarabaeoidea, Hybosoridae) from Madagascar, Zoosystema 30 (3), pp. 605-628 : 618-620

Genus Pseudosynarmostes n. gen.

TYPE SPECIES. — Pseudosynarmostes mitsinjo n. sp.

ETYMOLOGY. — From Ancient Greek ΨΕΥΔΟς (false) and Synarmostes , because the appearance of the beetle when rolled up is very similar to that of Synarmostes . The gender is masculine.

DISTRIBUTION AND HABITAT. — Madagascar, see under individual species for more details.

DIAGNOSIS. — Pseudosynarmostes n. gen. can easily be distinguished from all other known genera of Ceratocanthinae by the following combination of characters: 1) head with a deep furrow between the tip of fore margin and the vertical part of clypeus, which bears a distinct sexually dimorphic process; 2) antennae with first segment of club unusually expanded basally and oriented longitudinally ( Fig. 13F ); 3) female protibiae sharp and S-shaped ( Fig. 13B ); 4) female protibiae, when the beetle is rolled up, are not completely visible, but only a small portion is visible at sides ( Fig. 12B ); 5) mesotibiae having only one apical spur; and 6) a likely hint of genal suture visible on head.

DESCRIPTION

Small Ceratocanthinae , body dorsally shiny, ventrally alutaceous; setose; “rolling up” coaptations perfect; winged but possibly flightless.

Head wide (W/L ratio = 1.75), subrectangular, fore margin forming a very obtuse angle (about 145°, excluding apical acute process) in the middle, scarcely protruding forward and with apex slightly protruding in a small acute setose process sexually dimorphic ( Fig. 10A, B ), both sides of the process smooth and very slightly curved, not reflexed upward; genae aligned with fore margin, protruding outwards, forming a rounded right angle with genal canthus; genal canthus relatively narrow, straight and complete, touching the occipital area; dorsal ocular area small, dorsal interocular area about 10-11 times the maximum width of the dorsal ocular area, ventral ocular area large; head surface plane, with variable punctures, transversal striae and pubescence, a transverse line just before the gena (genal suture?).

Pronotum distinctly wider than long (W/L ratio = 2), slightly wider than elytra; fore margin finely beaded at middle and feebly bisinuate; fore angles slightly but distinctly protrudent forward, subtruncate; sides not beaded, obtusely rounded; base very finely beaded at middle; pronotal surface regularly convex, uniformly sculptured and setose.

Scutellum large, wider than long (W/L ratio = 1.5), sides proximally subparallel and notched by elytral articular process, then convergent to form a triangle with acute apex and sides slightly curved inward. Apical portion of mesepisterna hardly visible from above, distinctly smaller than elytral articular process.

Elytra slightly longer than wide (W/L ratio = 0.91), apical 4th regularly rounded (dorsal view), apex slightly re-entering inward (lateral view); elytra regularly convex without forming a distinct pseudoepipleuron; elytral suture very feebly raised, sutural stria extremely narrow and approaching to suture; inferior sutural stria present, although very finely impressed, delimiting a small marginal elytral area, with irregular surface sculpturing; striated articular area narrow, visible in lateral view, made of 5 or 6 striae; humeral area rounded, lacking a distinct humeral callus; elytral articular process normally developed, smooth and shiny.

Apical vertical extremity of clypeus short and transversely deeply grooved in a sexually dimorphic way, medially the groove is setose and notched upwards by the acute process of apex of head and downwards by a setose sexually dimorphic process ( Fig. 10A, B ). Labrum relatively narrow and short, bearing several long setae. Distal epipharynx ( Fig. 11H ) subrectangular, longitudinally divided by a sharp strong anterior median process; pariae distinctly raised with respect to the haptolachus; median brush and corypha absent; apical fringe made of long fine setae, absent in the middle. Labium ( Fig. 11E ) ventrally flat, deeply emarginated in the middle, emargination regularly narrow-U-shaped; labial palpi (including palpiger) 4-jointed, 1st joint short and very transverse, joint 2 very short and weakly sclerotized, joint 3 longer than preceding one and slightly curved, joint 4 subconical, all joints, apart from the last one, fringed with long setae. Maxillae ( Fig. 11F ) with an elongate single membranous lacinia, covered with fine long setae, monolobed galea proximally sclerotized and distally clothed with very coarse medium sized thick spatulate setae (galeal brush; Fig. 11G )), maxillary palpi (including palpiger) 4-jointed, palpiger very small, joint 2 wide and relatively short, joint 3 about as wide as long, joint 4 long and subconical, distinctly longer than the preceding 2 together, apically bearing some short sensilla. Mandibles ( Fig. 11 A-D) relatively long, slightly asymmetrical, outer margin regularly convex, apiculus preceded by a short vertical tooth, apiculus relatively long and acutely pointed, exceeding the mesal brush by one third of the length, mesal brush narrow and well-developed, molar lobe very strong. Antennae 10-segmented ( Fig. 13F ), scape long (about half the total length of antenna), distally slightly clavate/ securiform, distally bearing some setae, funicle short with pedicellus plump and rounded, the remaining articles very short, distinctly wider than long, antennal club made of 3 articles, the first one expanded basally, oriented almost longitudinally following the longitudinal axis of the last article of funicle, articles of club hairy, relatively small.

Ventral areas of prothorax, apart from the sides, setigerously punctured, setae long and recumbent. Hypomeron smooth, very folded in. Procoxae transversely oriented, apices nearly touching each other; fore trochanters relatively wide, with fore tips bearing a tuft of long setae; profemora slender, fore edge distinctly concave, surface smooth with few recumbent setae; protibiae sexually dimorphic ( Fig. 13A, B ), apical spur relatively long, sharp, distally curved downward, protarsi with 1st article slightly longer than the following articles together, articles 2 and 3 slightly dilated, article 5 slightly longer than the 4th article, bearing 2 short curved claws, each tarsomere, with the exception of the last one, ventrally bearing a tuft of coarse fine setae. Mesosternum narrow, short and plump, forming a sharp and fine carina protruding between mesocoxae and joining metasternum, mesocoxae large, almost adjacent to each other, longitudinally oriented, trochanters narrow, with hind tip acute, mesofemora slender, surface smooth, with hind edge emarginated at distal 3rd, emargination preceded by a small distinct tooth; mesotibiae ( Fig. 13C, D ) relatively short, sexually dimorphic, inner angle of apex with one straight apical spurs in both sexes, mesotarsi inserted near the inner angle of apical edge, slightly longer than apical edge of tibia, with first 3 articles subequal, 4th shorter, 5th almost as long as the preceding 2, bearing 2 small curved claws; each tarsomere, with the exception of the last one, ventrally bearing a tuft of coarse setae; trochanters of metafemora narrow, with hind tip acute, metafemora plumper than mesofemora, surface hairy, hind edge distally with a small emargination, metatibiae ( Fig. 13E ) triangular, very wide, flat, ending with 2 sharp fine spurs paired at the inner angle of the tibia, metatarsi almost as long as the apical edge of tibia, first article almost as long as the following 3 together, 5th almost as long as the first one, claws small and feebly curved; each tarsomere, with the exception of the last one, ventrally bearing a tuft of coarse setae. Outer face of meso- and metatibiae with longitudinal striae along inner margin and a variable sculpturing and setation along outer margin.

Wings ( Fig. 12A ) (L wing/L elytron ratio = 2.1): with reduced and poorly sclerotized venation, MP 1+2 -RP loop absent, RP2 relatively long (although weakly sclerotized), apical field with a small vertical secondary sclerification near the radial cell.

Sexual dimorphism: females have the acute process of apex of head more protruding forwards and bent upwards ( Figs 10B ; 14 ), grooves of vertical part of clypeus deeper and setose process of vertical part of clypeus larger and more setose than in males, female protibiae ( Fig. 13B ) sharpened and S-shaped, ending with 2 small short teeth, apical spur of protibiae plumper with tip more dramatically bent downwards, mesotibiae more narrowed apically ( Fig. 13C ) ending with a short process bent outwards marked by a tuft of short setae, whereas males have the protibiae normally shaped, with a broad distal part and ending with a single small outer tooth ( Fig. 13A ), apical spur of protibiae slender and more gently bent downwards, and mesotibiae almost straight, without any tuft of setae apically ( Fig. 11D ). While in the rolled up posture the female conceals the protibia, which in turn is normally visible in the male ( Fig. 12B ).

Male genitalia: genital segment fairly sclerotized. Aedeagus dorsally flattened with basal piece very slightly twisted, longer than parameres; internal sac relatively small, usually extroflected forwards; temones present; parameres dorsally flattened.

Female genitalia: no bursal sclerites and spermatheca weakly sclerotized; genital palpi weakly sclerotized, relatively small and short.

REMARKS

Both Fairmaire (1900) and Paulian (1979) stressed the unusual morphology of the habitus of Philharmostes perrieri , but, having only a single specimen at hand, they did not go further. Dissection of the holotype of P. perrieri and the collection of a long series of a new species in January 2006 allowed me to discover the unique antennal and head morphology as well as the unusual sexual dimorphism and therefore to find many autoapomorphies warranting the establishment of a new genus. The nearest affinities of Pseudosynarmostes n. gen. are unknown and the set of unique characters distinguishing this genus is truly amazing. No other Ceratocanthinae possess such a modified vertical part of clypeus with a groove so deeply excavated and the “setose process”. Th e secondary sexual dimorphism is particularly interesting and unique within the family ( Ballerio 2006). Th e female protibiae have a shape not found in any other known genus, being sharpened and S-shaped, this perhaps could be related to digging capabilities for egg laying. It is interesting to notice another unusual feature related to the shape of female protibiae: once rolled up the female of Pseudosynarmostes n. gen. does not show the outer face of protibiae ( Fig. 12B ), which in turn are regularly visible in the male. Possibly the morphology of aedeagus, head and mouthparts could suggest some similarities with Synarmostes and the continental African genera Melanophilharmostes Paulian, 1968 and Pseudopterorthochaetes Paulian, 1977 but the phylogenetic position of this new genus will be discussed in another paper. The metathoracic wings of Pseudosynarmostes n. gen. are relatively long, although they show a weak and reduced wing venation, so it is not possible to state whether the species in this genus are able to fly or not. It must also be observed that the humeral area is rounded and lacks a humeral callus, a typical feature related to flightlessness ( Scholtz 2000).

Figures

FIG. 13. — Pseudosynarmostes mitsinjo n. sp.: A, male protibia (chaetotaxy and puncturation omitted); B, female protibia (chaetotaxy and puncturation omitted);C, female mesotibia (chaetotaxy and puncturation omitted);D, male mesotibia (chaetotaxy and puncturation omitted); E, metatibia (chaetotaxy and puncturation omitted); F, antenna, arrow indicates the basal development of first segment of antennal club. Scale bar: A-E, 0.4 mm; F, 0.2 mm.

FIG. 12. — Pseudosynarmostes mitsinjo n. sp.: A, wing; B, outline of specimen once rolled up, left male and right female, hatched areas indicate the protibiae; C, outline of genital segment; D, aedeagus. Scale bar: A, B, 0.7 μm; C, D, 0.5 μm.

FIG. 10. — Pseudosynarmostes mitsinjo n. sp.: A, head of male; B, head of female (mouthparts removed). Arrows indicate: 1, apex of head; 2, groove between apex of head and setose process; 3, setose process. Scale bars: 100 μm.

FIG. 11. — Pseudosynarmostes mitsinjo n. sp. mouthparts: A, B, mandibles in dorsal view; C, D, mandibles in ventral view; E, labium and labial palpi; F, maxilla and maxillary palpus; G, detail of galeal brush; H, distal epipharynx. Scale bars: A-F, H, 80 μm; G, 20 μm.

FIG. 14. — Pseudosynarmostes perrieri (Fairmaire,1898) n. comb., dorsal view of female (Tsimembo forest). Scale bar: 1 mm