Triodontus nitidulus ( Guérin-Méneville, 1844 ), Guerin-Meneville, 1844

Frolov, Andrey V., Montreuil, Olivier & Akhmetova, Lilia A., 2016, Review of the Madagascan Orphninae (Coleoptera: Scarabaeidae) with a revision of the genus Triodontus Westwood, Zootaxa 4207 (1), pp. 1-93 : 61-66

Triodontus nitidulus ( Guérin-Méneville, 1844)

( Figs. 31 A–G; 32A–C)

Orphnus nitidulus Guérin-Méneville, 1844: 86 .

Triodontus nitidulus (Guérin-Méneville) : Westwood 1845: 173; Paulian 1937: 13, 1977: 1220. Triodontus occidentalis Paulian, 1977: 1220 , new synonym

Orphnus obsoletus Brancsik, 1893: 224 , new synonym

Type material examined. Orphnus nitidulus : lectotype (here designated, Fig. 32 A), male, “ Type Guerin Men / Type / Coll. R. I. Sc. N. B. Madagascar Orphnus nitidulus Guer. [...] ♂ Madag / Coll. R. I. Sc. N. B. Madagascar ex coll. Guerin ex coll. Monchicourt ex coll. de Bonneuil Le Moult vendit / TYPE / Orphnus M.Leay Madagascarensis Dup. Madag ” ( IRSNB) .

Orphnus obsoletus : one syntype ( Fig. 32 C), male, “Nosy Be” (FMNH).

Triodontus occidentalis : holotype ( Fig. 32 B), male, “ Berati D. Ananalava P. Griveaud XII.1960 / MUSEUM PARIS Madagascar / Triodontus occidentalis n. sp. R. Paulian det. / TYPE ” ; paratypes, one male and four females with the same locality data as the holotype .

Additional material examined. MADAGASCAR: Antsiranana: three males, 15 females, “ Madagascar-Est dct. Sambava Marojejy Ambinanitelo 500m XII-58 Raharizonina [ Sambava District , Ambinanitelo]” ( MNHN) ; six males, four females, “ Madagascar Est 17.XIII.72 Marojejy 300 m. [ Marojejy Range , 300 m, 17.XIII.1972]” ( MNHN) ; two males, two females, “ Andranovolo / Madagascar R-on Antalaha XII.38 Vadon [R-on Antalaha , Andranovolo , 15°01′59″S, 50°07′00″E]” ( MNHN) ; one male, “ Madagascar Est m-if du Marojejy env-ons Manantenina 150 m., II.1974 A.Peyrieras [Marojejy Range, environs of Manantenina, 14°28′59″S, 49°49′00″E]” ( MNHN) ; 21 males, 35 females, “ Madagascar Ron Antalaha [ Antalaha District ] XI.35 Vadon ” ( MNHN) ; one male, “ Marojejy 400m f[or]et Ambatomitatao A. Peyrieras I.1973 [ Ambatomitatao Forest , Marojejy Nature Reserve, 14°25′59″S, 49°43′59″E]” ( MNHN) ; three males, “ Madagascar Ron Antalaha XII.35 Vadon Andapa [Antalaha District, Andapa , 14°39′00″S, 49°39′00″E]” ( MNHN) ; eight unsexed specimens, “ Sambirano [13°43′00″S, 48°22′00″E] N.O. Madagasc. ” ( SMTFD) ; three females, “ Madagascar Andapa 1.69 [ Andapa , 14°39′00″S, 49°39′00″E]” ( IRSNB) ; Toamasina: one male, “ Reserve nat III Ambatovositra Andranomalaza I-57 P Soga [ Ambatovositra , Andranomalaza , " Reserve naturelle III", 17°39′00″S, 48°37′00″E]” ( MNHN) ; seven males, four females, “ Madagascar Est Moramanga -57 Gruvel [ Moramanga , 18°55′59″S, 48°12′00″E]” ( MNHN) ; 42 males, 16 females, “ Nandihizana / Madagascar R-ne Maroantsetra XII.1938 Vadon ! [ Maroantsetra District , Nandihizana , 15°45′00″S, 49°19′00″E]” ( MNHN) ; one male, “ Madagascar Beanana XII.45 Vadon! [ Beanana , 15°43′59″S, 49°28′00″E]” ( MNHN) ; six males, six females, “Museum Paris Madagascar Andevorante A. Mathiaux 1900 [ Andevoranto , 18°57′00″S, 49°06′00″E, 1900, A. Mathiaux leg.]” ( MNHN) ; 52 males, 16 females, “ Madacascar Antsianaka et lac Alaotra 2e Trimestre 1889 Perrot Freres [Antsianaka and Alaotra Lake , 17°30′00″S, 48°30′00″E]” ( MNHN) ; three males, five females, “ Madagascar Fenerive E.Perrot [ Fenerive , 17°22′00″S, 49°25′00″E]” ( MNHN) ; two males, three females, “ Madagascar Analamazoatra / Museum Paris 1931 Lasere ” ( MNHN) ; four males, two females, “ Madacascar Antsianaka Perrot Freres 2 Semestre 1890 [ Antsianaka , 17°30′00″S, 48°30′00″E]” ( MNHN) ; one male, two females, “ Madagascar-Est dct. Moramanga Fanovana X I-58 R.Vieu [Moramanga District, Fanovana , 18°55′00″S, 48°34′00″E]” ( MNHN) ; one male, “ Madagascar Est distr. Mananara - N. Antanambe Vadon et Peyrieras [Mananara District, Antanambe , 16°25′59″S, 49°51′00″E]” ( MNHN) ; two females, “Museum Paris Madagascar Prov. de Fenerive Reg. de Soanierana A. Mathiaux 1905 [District of Soanierana (= Soanierana Ivongo )]” ( MNHN) ; one female, “ Madagascar Brickaville [18°49′00″S, 49°04′00″E] Cap. Refroigney [?].” ( MNHN) ; one female, “ Perinet [18°55′59″S, 48°25′00″E]” ( MNHN) ; one male, “Museum Paris Madagascar Env. de Tamatave A. Raffrey 1884 [ Tamatave (= Toamasina), 18°10′00″S, 49°22′59″E]” ( MNHN) ; one male, “ Madagascar Tamatave prov. Moramanga env. [ Moramanga environs, 18°55′59″S, 48°12′00″E] 27– 30.12.1996 Ivo. Jenis leg.” ( MHNG) ; one male, two females, “ Madagascar Tamatave prov. Andasibe (Maromizaha) [ Forest Maromizaha , Anevoka , 18°57′00″S, 48°28′00″E] 19 – 20.12.1996 Ivo. Jenis leg.”; one male, “ Madagascar Tamatave prov. Andasibe (Maromizaha) [ Forest Maromizaha , Anevoka , 18°57′00″S, 48°28′00″E] 21 – 24.11.1995 Ivo. Jenis leg.” (MHNG); 14 males, five females, “Rogez Madagascar Mus Praha 800–990 m [ Rogez , 800–990 m, 18°47′53″S, 48°36′05″E]” ( NMPC) ; 71 unsexed specimens, “ Madagascar C. Moramanga env. [ Moramanga , 18°55′59″S, 48°12′00″E] 10–18.XII.1997 P.Pacholatko leg.” ( NHMB) ; 41 unsexed specimens, “ Tamatave [Toamasina, 18°10′00″S, 49°22′59″E], 1884, A. Raffrey leg., ( SMTFD) ; one male, “ Maroantsetra [15°25′59″S, 49°43′59″E] Madagasc. ” ( SMTFD) ; one male, “ Moramanga [18°55′59″S, 48°12′00″E] Madagasc. or.” ( SMTFD) ; one male, “mittl. O.-Madag. Ambalarond[r]a Dr.Denso 1931.11 [ Ambalarondra , 18°28′06″S, 49°00′04″E, XI.1931, Denso leg.]” ( SMTFD) ; eight males, two females, “ Tamatavo [ Tamatave (= Toamasina), 18°10′00″S, 49°22′59″E] Madagascar ” ( IRSNB) ; Antananarivo: eight males, four females, “Museum Paris Madagascar Antsirabe Waterlot 1916 [ Antsirabe , 19°51′00″S, 47°01′59″E, 1916, Waterlot leg.]” ( MNHN) ; one male, “ Andrangoloaka 1600 m O.S.O. de Tananarive [ Andrangoloaka , 1600 m, 19°01′00″S, 47°52′00″E]” ( MNHN) ; three males, 10 females, “ Madagascar Tanarive III.33 [Antananarivo, 18°55′00″S, 47°31′00″E] / Museum Paris 1933 J.Vadon et E.Lebis ” ( MNHN) ; two females, “ Madagascar Est Ankadimanga Manjakandriana XII-57 Jean-Elie [Ankadimanga, Manjakandriana , 18°58′00″S, 47°45′00″E]” ( MNHN) ; one male, one female, “ Madagascar Ambatolampy [19°22′59″S, 47°25′00″E]” ( MNHN) ; one female, “ Madagascar Tananarive Vadon! [ Antananarive , 18°55′00″S, 47°31′00″E]” ( MNHN) ; eight males, five females, “ Madagascar La Mandraka Vadon! XII-36 [ La Mandraka , 18°55′00″S, 47°55′59″E]” ( MNHN) ; one male, “ Tananarive III.33 [ Antananarive , 18°55′00″S, 47°31′00″E]” ( MNHN) ; one female, “ Madagascar Antananarivo prov. Manankazo env. [18°09′00″S, 47°12′00″E] 15– 17.12.1996 Ivo. Jenis leg.” ( MHNG) ; 22 unsexed specimens, “ La Mandraka [18°55′00″S, 47°55′59″E] II.1953 Madagascar ” ( NHMB) ; Fianarantsoa: eight males, 14 females, “ Madagascar Region de Mananjary [21°13′00″S, 48°19′59″E] A. Mathiaux ” ( MNHN) ; two males, “ Madagascar: Prov. Fianarantsoa, Ranomafana, 600 m. [ Ranomafana , 600 m, 21°18′00″S, 47°30′00″E] 21 October 1988 W.E.Steiner & R. Van Epps collrs.” ( MNHN) ; five females, “ Madagascar Centre dct. Ambohimahasoa foret Tsarafidy 1450 m XII-59 & I . 60 P. Griveaud [Ambohimahasoa Disctrict, Ankafina Tsarafidy, forest Tsarafidy , 1450 m, 21°12′00″S, 47°15′00″E]” ( MNHN) ; two females, “ Madagascar Vohilava 60 m. Faraony [ Vohilava Faraony , 60 m, 21°46′00″S, 47°55′00″E]” ( MNHN) ; four males, two females, “ Ambositra [20°31′00″S, 47°15′00″E] Madagascar ” ( MNHN) ; six males, six females, “ Madagascar Fianarantsoa prov. Ranomafana env. [21°18′00″S, 47°30′00″E] 29.11.– 2.12.1995 Ivo. Jenis leg.” ( MHNG) ; one female, “MADAGASCAR - CE 2010 Ranomafana NP ~ 1120 m Vohiparara env., at light on river bank [Ranomafana National Park, Vohiparara environs, ca. 1120 m, 21°13′35″S, 47°22′11″E]; 17.XI. local coll. lgt. , BMNH(E) 2010-29 ” (BMNH); two unsexed specimens, “Ambositra Madagascar 14.11.55 G.Minet [ Ambositra , 20°31′00″S, 47°15′00″E]” ( NHMB) ; one male, “ MADAGASCAR, Fianarantsoa Province, Ranomafana National Park, Vohiparara area , 1170 m, mixed tropical forest. 2–22 January 2001, 21.22644°S / 47.36979°E. Stop# DHK-01-004 D.H. & K.M. Kavanaugh. R.L. Brett, E. Elsom, F. Vargas, R. Ranaivosolo, E.F. Randrianirina, N. Rasoamananana, T.J. Ravelomanana, and H.C. Raveloson leg.” ( CASC) ; one female, “ MADAGASCAR, Fianarantsoa Province, Ranomafana National Park, Talatakely area , 900 m, mixed tropical forest 2–22 January 2001, 21.25041°S / 47.41945°E, COL-DHK-2001-001 D.H. & K.M. Kavanaugh. R.L. Brett, E. Elsom, F. Vargas, R. Ranaivosolo, E.F. Randrianirina, N. Rasoamananana, T.J. Ravelomanana, and H.C. Raveloson leg.“ ( CASC) ; one male, “ MADAGASCAR, 2007, Ranomafana Nat. Park near Ranomafana vill. [21°18′00″S, 47°30′00″E], M. Tryzna leg., 26–31.i. , BMNH(E) 2010-29 [26–31.I.2007, M. Tryzna leg.]” (BMNH); three males, three females, “ MADAGASCAR CE 2011 , Ranomafana N. P. [ Ranomafana National Park ] 17–21.xi. S 21°15'22.6'' E 47°25'17.8'' 958 m; at light; M. Tryzna leg . BMNH(E) 2010-29 ” (BMNH); one male, “Deans Cowan Betsileo Madagascar / 1881 3000 ft 4000 ft [3000–4000 ft, 1881]” ( SMTFD) ; one male, “ Ifanadiana [21°18′12″S, 47°38′19″E] Madagascar Mus. Praha ” ( NMPC) ; one male, three females, “ Masagascar Midongy [ Midongy-du-Sud , 23°35′13″S, 47°01′00″E]” ( NMPC) ; Mahajanga: 57 males, 14 females, “S te Marie de Madagascar Perrot Freres X–XII 1896 [Sainte Marie de Madagascar, near Marovoay , 16°06′00″S, 46°37′59″E]” ( MNHN) ; one male, one female, “ Berati D. Ananalava P. Griveaud XII.1960 [Ananalava District, Beraty , 14°01′00″S, 48°15′00″E]” ( MNHN) ; one female, “ Randiantsileo / Madagascar Ron Mandritsara XII-37 Vadon! [Randiantsileo, Mandritsara District ]” ( MNHN) ; three females, “ Morafenobe [unclear locality] Madag. occ.” ( SMTFD); one male, “Maromandia [14°13′00″S, 48°04′59″E] Masagascar Mus . Praha ” ( NMPC) ; 79 males, 20 females, “Coll. IRScNB MADAGASCAR Sainte Marie de Madagascar [16°06′00″S, 46°37′59″E] 1897 Ex. Coll. Oberthur ” ( IRSNB) ; Toliara: one male, one female, “ Madagascar Ouest Bongolava 1300 m. [ Bongolava , 18°30′00″S, 45°30′00″E] / A.Peyrieras XII.1974 ” ( MNHN) ; one female, “Betroka XI.31 [ Betroka , 23°16′00″S, 46°04′59″E, XI.1931]” ( MNHN) ; Madagascar (no precise locality): two females, “ Madagascar E.Perrot ” ( MNHN) ; six unsexed specimens, “ Madagascar ” ( SMTFD) .

Diagnosis. Triodontus nitidulus is most similar to T. bicavatus . Males of the former species can be separated by having abdominal sternite 8 narrower and more sinuate medially, without oval transverse concavity ( Fig. 31 F), and by having the lateral lobes of the parameres without small keel-shaped processes on proximal parts ( Fig. 31 E). Females of these species are difficult to separate.

Description. Male. Color of head, pronotum and elytra dark brown; legs, antennae, and underside of the body brown ( Fig. 31 A).

Frontoclypeus convex anteriorly, rounded laterally, anterior margin crenulate and setose in dorsal view. Eyes relatively small (diameter slightly smaller than the distance between eye and gula in ventral view), incompletely divided by canthus into small, dorsal and large, ventral parts. Frontoclypeus with small tubercles mediad of each eye and in some specimens with a horn in the center of the frontoclypeus. The horn, when the most developed, is about as long as the width of the head, acutely rounded apically, straight to somewhat curved caudally at the apex, slightly rugose on posterior side.

Pronotum with a bulge medially, with excavations aside the bulge, and with 2 ridge-shaped tubercles laterally of each excavation. The median bulge has 3 small but distinct tubercles. Lateral margins with wide border appearing somewhat crenulate in dorsal view, with a row of brown setae. Anterior margin with wide, smooth border. Posterior margin with fine border, not crenulate, punctate with narrow longitudinal punctures. Surface of most pronotum smooth, anterior and posterior angles with sparse and coarse punctation.

Scutellum rounded apically, visible part about 1/12 length of elytra.

Elytra convex, with distinct humeral humps, their maximum width is approximately at the middle. Elytra with 10 distinct striae on disc and with oblique line from base of 6th stria to approximately middle of 8th stria. Stria with small punctures. Intervals with minute punctures, almost smooth. Base of elytra with an irregular row of coarse punctures.

Sternite 8 medially deeply sinuate (in ventral view) and somewhat excavated ( Fig. 31 F).

Parameres ( Fig. 31 E) with large outer lobes covering inner lobes (in lateral view). Proximal parts of outer lobes without keel-shaped processes. Internal sac of the aedeagus with 1 strongly sclerotized symmetrical sclerite, somewhat horseshoe shaped, and with 2 similar protuberances of the membrane ( Fig. 31 D).

Female. Females ( Fig. 31 C) differ from males in having a long, apical spur on the protibiae; absence of the head and pronotum armature including tubercles mediad of each eye; densely punctate dorsal side of the head; and longer abdominal sternites including 6th sternite, which is evenly rounded apically.

Variation. Pronotal and head armature of males is subject to allometric variability from fully developed (as described above) to almost undeveloped (with the males having small frontoclypeal tubercles in the middle and small fossa on the pronotum anteriorly. Body length of examined specimens varied from 6.5–9.0 mm (males) and from 6.0– 7.5 mm (females).

Remarks. The lectotype of T. nitidulus was unknown to Paulian (1977). We found one male specimen originated from the collection of Guérin-Méneville and deposited now in IRSNB. This specimen agrees with the original description of the species. Since Guérin-Méneville mentioned both sexes, evidently he examined more than one specimen although he provided no exact data on this account. To ensure the stability of the nomenclature, we designate this specimen ( Fig. 32 A) the lectotype of Orphnus nitidulus Guérin-Méneville, 1844 .

Brancsik (1893), in the original description of O. obsoletus , noted that it was similar to O. nitidulus (= T. nitidulus ). From the short diagnosis of the former, it can be inferred that it differs from the later mostly in the less developed head and pronotum armature. Paulian (1977) considered O. obsoletus a junior synonym of T. bicavatus , however he did not discuss this synonymy. Examination of the male syntype of O. obsoletus showed that it has all the diagnostic characters of T. nitidulus , including the characteristic shape of the abdominal sternite 8, therefore the new synonymy is here proposed.

Paulian (1977) distinguished T. occidentalis Paulian from T. nitidulus by the absence of the fossette on the abdominal sternite 8 in the males of the former (as opposed to the presence of a “vague fossette” in the later). However T. nitidulus has no distinct fossette or fovea on the abdominal sternite 8 (as in T. bicavatus ) but rather its abdominal sternite 8 is apically sinuate and somewhat excavated, that may appear “foveate” depending on the angle of view. We found no noticeable differences between the type of T. occidentalis and available material of T. nitidulus and hence we propose the new synonymy.

Distribution and habitat. This is the most widespread and the only relatively abundant species of the Orphninae in Madagascar. It is currently known from 50 localities throughout the island ( Fig. 31 G). Most of the localities are in the eastern Madagascar, in the area occupied by primary and secondary forests. The relatively wide distribution and high abundance of this species may be, at least partly, a result of the secondary adaptation to feeding on cultivated crops. Larvae of T. nitidulus were collected in upland rice fields in the Central Plateau ( Randriamanantsoa et al. 2010).

Figures

FIGURE 31. Triodontus nitidulus. Habitus in dorsal view (A—male, C—female), head and pronotum of male in dorsolateral view (B), internal sac of aedeagus (D), aedeagus in lateral view and parameres in dorsal and ventral view (E), abdomen (F), distributional records (G).

FIGURE 32. Triodontus nitidulus. Habitus of in dorsal view. Lectotype of T. nitidulus (A), holotype of T. occidentalis (B), syntype of T. obsoletus (C).