Madecorphnus Paulian, 1992
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publication ID |
https://doi.org/ 10.1080/00222931003632765 |
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persistent identifier |
https://treatment.plazi.org/id/787F360B-1E2F-FF81-E3E5-DB69C9081B05 |
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treatment provided by |
Felipe |
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scientific name |
Madecorphnus Paulian, 1992 |
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Type species Drepanognathus falciger Lansberge, 1886 , designated by Paulian (1977). = Drepanognathus Lansberge, 1886 , pars.
= Sissantobius Ritsema, 1888 : Paulian, 1977, pars.
Diagnosis
Small-sized beetles (4.5–5.0 mm) with mostly uniform, brown to black colouration. Clypeus symmetrical to asymmetrical in males, wide, bordered anteriorly. Mandibles asymmetrical, subequal in length in females and subequal to strongly unequal in males. Head smooth. Frontal tubercles absent. Pronotum wider than long, smooth, lateral margins bordered, with four to five long setae. Disc of pronotum similar in both sexes, without any depressions, tubercles, or ridges. Elytra with only first stria distinct. Scutellum triangular, widely rounded apically, about 1/10 length of elytra. Wings fully developed. Parameres symmetrical. Internal sac of aedeagus with one or a few sclerites.
The members of Madecorphnus have a number of characters which distinguish the genus from other Orphninae and which are uncommon or unique among the Scarabaeidae . First, the mandibles in males may be highly asymmetrical in both shape and length. In some specimens, the right mandible is twice as long as the left one or even longer. Such specimens also have a clearly asymmetrical clypeus ( Figures 1, 3–7 View Figures 1–19 ). The shape of the mandibles is species-specific at least in some species, but it is subject to allometric variability and, therefore, cannot always be a reliable diagnostic character.
The second feature, characteristic of the genus, is the presence of a few long setae on the sides of the body and head; the setae have distinct numbers and locations. In general, pubescence of the body is extremely diverse in scarab beetles, ranging from almost absent in some groups to very dense, long, and almost completely hiding sclerites in others. It is subject to some variation within and among species and often differs in the different sexes. Pubescence of the body is widely used in species identification. However, as far as I know, individual homologizable setae, at least on the pronotum and elytra, have not been described in the Scarabaeidae . All the Madecorphnus species except for two possess the following symmetrically located long setae ( Figure 1 View Figures 1–19 ): one seta on elytral base near epipleuron, one seta on posterior angle of pronotum, one seta approximately in the middle of lateral margin of pronotum, two setae on the anterior angle of pronotum, two setae on each gena, and two setae on the anterior margin of clypeus. As an exception, M. pauliani sp. nov. has three setae on each anterior angle of pronotum and a female of M. dentatus sp. nov. has two setae on the hind angle. Even if one or a few of these setae are absent, there is no doubt that they were lost as a result of abrasion, since in the places where they should be according to the scheme given previously, there are characteristic foveae with chaetiferous pores. There are no other setae on the dorsal side of the body except for mouthparts. There are long, relatively sparse setae on epipleura and ventral side of thorax, but they do not have definite locations. Also, often there are small setae on the anterior margin of clypeus.
The third feature that distinguishes Madecorphnus among other Orphninae is a weaker sexual dimorphism. The sexes mostly differ in the shape of the mandibles. Males with relatively feebly developed mandibles are similar to females. In Madecorphnus , the sexual dimorphism character common for all Orphninae genera, namely the absence of distinct anterior tibial spur in males, is less expressed than in other genera. Often, the apical seta is longer and more robust than others and it is similar to the spur. Madecorphnus males also lack any clypeal horns and prothoracic ridges and excavations which are found in majority of species of almost all genera of Orphninae .
Distribution and bionomy
Judging from the known collecting localities ( Figure 31 View Figure 31 ), Madecorphnus species are distributed throughout Madagascar but mostly in the eastern part of the island. The notable exception is M. falculoides which was found in the western part. The majority of the localities agree well with current distribution of remnants of indigenous forests. This suggests that forest is the preferred habitat for Madecorphnus . However, collecting might be biased since more insect sampling was done in the forests than in the arid central and western Madagascar.
Almost nothing is known about bionomy of Madecorphnus . The labels of the collected specimens lack any data about the way the beetles were collected. It is possible that Madecorphnus species are generally saprophagous litter dwellers. They might also be attracted to carrion like Pseudorphnus hiboni Paulian ( Frolov and Montreuil 2006). Nesting behaviour and preimaginal stages are so far unknown.
Key to the Madecorphnus species (males)
1.
Right mandible with a tooth on inner side of scissorial part ( Figures 1, 3 View Figures 1–19 )
........................................................ 2 Right mandible without a tooth on inner side of scissorial part ( Figures 2, 4, 5 View Figures 1–19 )
............................................................ 3 2. Parameres slender in dorsal view ( Figure 8 View Figures 1–19 ). Internal sac of aedeagus with two large bifurcated sclerites and a few dozen spinules ( Figure 20 View Figures 20–30 ). Mentum without tubercles............................. M. falculoides Paulian Parameres wider in dorsal view, with one small tooth each ( Figure 9 View Figures 1–19 ). Internal sac of aedeagus with two bifurcated sclerites, without smaller spinules ( Figure 21 View Figures 20–30 ). Mentum with two tubercles........... M. montreuili sp. nov. 3. Apices of parameres without lateral teeth ( Figures 10, 11 View Figures 1–19 ).......... 4 Apices of parameres with more or less developed lateral teeth ( Figures 12–19 View Figures 1–19 )................................................... 5 4. Parameres without lateral excavations, about 1.5 times longer than basal sclerite of aedeagus ( Figure 10 View Figures 1–19 ).................... M. pauliani sp. nov. Parameres with lateral excavations, about two times longer than basal sclerite of aedeagus ( Figure 11 View Figures 1–19 )........................... M. niger sp. nov. 5. Head and pronotum with fine dense punctuation. Internal sac of aedeagus with three large sclerites and an area with smaller spinules ( Figure 23 View Figures 20–30 ).....
............................................ M. punctatus sp. nov. Head and pronotum with indistinct to sparse punctuation (punctures separated by at least three times their diameter). Internal sac of aedeagus with different armature............................................. 6 6. Parameres with large lateral teeth ( Figure 13 View Figures 1–19 )........ M. dentatus sp. nov. Parameres with small lateral teeth ( Figure 14–19 View Figures 1–19 ).................... 7 7. Internal sac of aedeagus with one sclerite composed of two long slender spinules connected basally ( Figure 25 View Figures 20–30 ).............. M. simplex sp. nov. Internal sac of aedeagus with two or more separate sclerites............ 8 8. Parameres with small teeth at extreme apex ( Figure 14 View Figures 1–19 , lateral view). Larger (7.0 mm)...................................... M. falcatus Paulian Parameres of different shape. Smaller than 6.0 mm................... 9 9. Parameres with angulate lateral teeth ( Figure 16 View Figures 1–19 ). Internal sac of the aedeagus with two large semicircular sclerites and one long spur-shaped sclerite ( Figure 27 View Figures 20–30 )................................. M. fasciger (Lansberge) Parameres with small lateral teeth. Internal sac armature different...... 10 10. Parameres less acute in lateral view ( Figure 17 View Figures 1–19 ). Internal sac of the aedeagus with one longer sclerite and one smaller, somewhat bifurcated sclerite ( Figure 28 View Figures 20–30 )................................... M. brunneus sp. nov.
Parameres more acute in lateral view ( Figures 18–19 View Figures 1–19 ). Internal sac with two longer and two smaller sclerites ( Figures 29, 30 View Figures 20–30 ).....................11
11. Parameres less tapering apically, lateral teeth closer to paramere apices ( Figure 18 View Figures 1–19 ). Eyes somewhat larger ( Figure 6 View Figures 1–19 )...... M. perinetensis sp. nov. Parameres more tapering apically, lateral teeth not so close to paramere apices ( Figure 19 View Figures 1–19 ). Eyes somewhat smaller ( Figure 7 View Figures 1–19 ).... M. peyrierasi sp. nov.
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