Rhantus latus (Fairmaire, 1869)

Hjalmarsson, Anna Emilia, Bukontaite, Rasa, Ranarilalatiana, Tolotra, Randriamihaja, Jacquelin Herisahala & Bergsten, Johannes, 2013, Taxonomic revision of Madagascan Rhantus (Coleoptera, Dytiscidae, Colymbetinae) with an emphasis on Manjakatompo as a conservation priority, ZooKeys 350, pp. 21-45 : 30-35

Rhantus latus (Fairmaire, 1869) Figures 2d, 3 g–i, 4c, 5 e–f, 6 e–f, 7 e–f, i

Colymbetes latus Fairmaire, 1869: 191. Type locality: Madagascar

Rhantus goudoti Sharp, 1882: 623. Synonymized by Branden (1885: 91). Type locality: Madagascar

Rhantus stenonychus Régimbart 1895: 179 syn. n. Type locality: Madagascar, lake Ambodinandohalo

Rhantus latus (Fairmaire, 1869): Régimbart (1895: 183); Zimmermann (1920: 202); Guignot (1961: 764); Nilsson (2001: 51).

Type material studied.

Typematerial of Colymbetes latus could not be localized in the Paris collections. We have no reasons to believe the type material is lost or destroyed, but to localize and identify the material that Fairmaire studied proved difficult as it was not found in Fairmaire’s collection. The type material was collected by medicine doctor and entomologist Charles Coquerel who died in 1867.

Rhantus stenonychus : Holotype♂ for Rhantus stenonychus (MNHN): "Madagascar, Lac Ambodo, R.P. Camboue", "Data in NHRS-JLKB000030296".

Rhantus goudoti: Lectotype♂ for Rhantus goudoti , here designated to fix the concept of Rhantus goudoti Sharp and to ensure the universal and consistent interpretation of the same (BMNH): “905”, "C. latus Fairm. seems very close to this, but is a little shorter in form, +paler" [handwritten note on the specimen], "Sharp Coll. 1905 –313.”, “Type”, "Type 905 Goudoti Dej. Madagascar." "Data in NHRS-JLKB 000030415", our lectotype label. Paralectotype♀ (BMNH) "Sharp Coll. 1905 –313.”, “Co-type”, "Madagascar. 905" "Data in NHRS-JLKB 000030413", our paralectotype label. Paralectotype♂ (BMNH) “37” “Co-type”, "Madagascar 905", "Sharp Coll. 1905 –313.” "Data in NHRS-JLKB 000030414"our paralectotype label. 1♂Paralectotype (MNHN): Data in NHRS-JLKB 000030297, Colymbetes goudotii mihi Madagascar, D. Sharp Monogr., Ex Musæo Dejean, our paralectotype label.

Additional material studied (for full details see Appendix).

Vakinankaratra region (former provinces: Antananarivo): 15spp. (Cat No. NHRS-JLKB000010277), Manjakatompo [2km NE Amparandraindrisa][pond and stream][MAD11-18], 19.3607S, 47.3009E, 1770m, 05.xi.2011, Leg. Bergsten, Ranarilalatiana, Randriamihaja, Bukontaite, 24 spp. (Cat. No. NHRS-JLKB000010278), Manjakatompo [500m E Lac Froid by the road][pond and inlet stream][MAD11-16], 19.3449S, 47.3338E, 1620m, 04.xi.2011, Leg. Bergsten, Ranarilalatiana, Randriamihaja, Bukontaite, 12 spp. (Cat. No. NHRS-JLKB000010274), Manjakatompo [Analafandriana, 500m S fish farm by the road][grassy pond][MAD11-14], 19.3619S, 47.3150E, 1730m, 03.xi.2011, Leg. Bergsten, Ranarilalatiana, Randriamihaja, Bukontaite, 1sp. (Cat. No. NHRS-JLKB000010269), Manjakatompo [Analamitana, by bridge close to SKOL facility][stream and stagnant pool][MAD11-19], 19.3646S, 47.2989E, 1750m, 05.xi.2011, Leg. Bergsten, Ranarilalatiana, Randriamihaja, Bukontaite, 2sp. (NHRS-JLKB000010270), Manjakatompo [Analafandriana close to fish farm][stream and wet field][MAD11-13], 19.3581S, 47.3140E, 1730m, 03.xi.2011, Leg. Bergsten, Ranarilalatiana, Randriamihaja, Bukontaite, 1sp. (Cat. No. NHRS-JLKB000021026), Manjakatompo [Tavolatara][pool near stream][MJK12-09], 19.3491S, 47.2780E, 2050m, 24.i.2012, Leg. Ranarilalatiana, Randriamihaja, 2spp. (Cat. No. NHRS-JLKB000021027), Manjakatompo [Analamitana] [swamp near stream][MJK12-02], 19.3640S, 47.2991E, 1760m, 22.i.2012, Leg. Ranarilalatiana, Randriamihaja, 2spp. (Cat. No. NHRS-JLKB000021028), Manjakatompo [Tavolatara][swamp near source][MJK12-10], 19.3496S, 47.2779E, 2050m, 24.i.2012, Leg. Ranarilalatiana, Randriamihaja, 3spp. (cat. No. NHRS-JLKB000021029), Manjakatompo [Anosiarivo][lake near source][MJK12-13], 19.3449S, 47.3041E, 2070m, 24.i.2012, Leg. Ranarilalatiana, Randriamihaja, 2spp. (Cat. No. NHRS-JLKB000021030), Manjakatompo [Poste][lake with grass][MJK12-14], 19.3542S, 47.3081E, 1800m, 24.i.2012, Leg. Ranarilalatiana, Randriamihaja, 5sp. (Cat. No. NHRS-JLKB000021031), Manjakatompo [Andohariana][small lake][MJK12-07], 19.3677S, 47.3143E, 1710m, 24.i.2012, Leg. Ranarilalatiana, Randriamihaja, 10spp. (Cat. No. NHRS-JLKB000021032), Manjakatompo [near camping][big temp. lake][MJK12-15], 19.3630S, 47.3171E, 1710m, 25.i.2012, Leg. Ranarilalatiana, Randriamihaja.

Alaotra Mangoro region (former provinces: Toamasina): 1 ♂ (Cat. No. NHRS-JLKB000030407), Mantadia, NP, Rianila Basin, [affluent non nommé riv.], [PO670], 18.935S, 48.4167E, 920m, 29.xi.1996, Leg. Legrand, Randriamasimanana, 1sp. (Cat. No. NHRS-JLKB000010268), Mantadia NP [3km from park entrance][open pond with vegetation][MAD11-42], 18.8526S, 48.4272E, 920m, 13.xi.2011, Leg. Bergsten, Ranarilalatiana, Randriamihaja, Bukontaite, 1♀ (Cat. No. BMNH-829991), Andasibe NP [entry to park, Anamalozaotra river and pond][P61Bi01], 18.9348S, 48.4175E, 950m, 04.i.2007, Leg. Isambert et al., 2♂ (Cat. No. NHRS-JLKB000030295), Antsianaka, 1892, Leg. Perrot, Perrot, 1♂ (Cat. No. NHRS-JLKB000030289), Ambatosoratra, env. Tananarive, vii.1934, Leg. Olsoufieff.

Matsiatra Ambony (Haute Matsiatra) region (former provinces: Fianarantsoa): 1sp. (Cat. No. BMNH-742359), Sendrisoa, S of Ambalavao, [P38], 22.0098S, 46.9504E, 1160m, 07.v.2006, Leg. Bergsten et al., 1sp. (Cat. No. BMNH-742090), Andringitra NP [Zomandao river, by bridge on road to camp Belamba], 22.1043S, 46.9207E, 1420m, 09.v.2006, Leg. Bergsten et al., 1♂ (Cat. No. BMNH-829990), Ambalavao, 15km SW of, RN7.

Amoron’i Mania region (former provinces: Fianarantsoa): 6spp. (Cat. No. BMNH-729860, 729861, 729862, 729863, 729864, 829992), Col des Tapia, 48 km N Ambositra, RN7, [P30MD33], 20.2388S, 47.1002E, 1440m, 08.xii.2004, Leg. Balke et al., 1♂ (Cat. No. BMNH-741961), Ambositra, 34km S of, RN7, 20.7719S, 47.1810E, 1690m, 06.v.2006, Leg. Bergsten et al.

Melaky region (Former provinces: Mahajanga): 1♂, 1♀ (Cat. No. NHRS-JLKB000000089, 000000090), Ambohijanahary NP [MAD09-76], 18.2685S, 45.4635E, 910m, 19.xii.2009, Leg. Bergsten, Ranarilalatiana, Randriamihaja, Jönsson

Atsimo Andrefana region (former provinces: Toliara): 3spp. (Cat. No. BMNH-742641, 742639, 742640), Zombitse-Vohibasia NP [Isoky, Ranomena, muddy pool in river basin], 22.6401S, 44.8644E, 580m, 15.v.2006, Leg. Bergsten et al., 1sp. (Cat. No. BMNH-741979), Zombitse-Vohibasia NP [edge of, Ambiamena, stagnant zebu-visited marshland, muddy & vegetation], 22.8601S, 44.6173E, 530m, 14.v.2006, Leg. Bergsten et al.

Ihorombe region (former provinces: Fianarantsoa): 1sp. (cat. No. BMNH-741810), Isalo NP [Menamaty river][river with vegetation][P41AM01], 22.5500S, 45.4012E, 760m, 11.v.2006, Leg. Bergsten et al.

Analamanga region (former provinces: Antananarivo): 1♂ (Cat. No. NHRS-JLKB000030282), Antananarivo [city or province, indecisive], 31.v.1947, Leg. Clement, 1♂ (Catl. No. NHRS-JLKB000030288), Lac Tsimbazaza, Antananarivo, 18.9333S, 47.5333E, 1410m, vii.1934, Leg. Vadon, 1♂ (Cat. No. NHRS-JLKB000030284), Andrang, Leg. Sikora, 1♂ (Cat. No. NHRS-JLKB000030285), Ambohibeloma, Leg. Sikora.

Madagascar (region indecisive): 2♂, 1♀ (Cat. No. NHRS-JLKB000030406, 30408, 30409), Madagascar, vii.1968 - ix.1968, Leg. Starmühlner, 1sp. (Cat. No. BMNH-729851), Madagascar, 1♂ (Cat. No. NHRS-JLKB000030286), Madagascar [Centre-Sud], Leg. Alluaud.

Diagnosis.

Pronotum somewhat infuscated and with one wide black spot, not divided medially (Figure 2d). Maleprotarsal claws long and slender, almost twice the length of last tarsal segment, somewhat sinuated and unequal, anterior claw longer (Figure 5 e–f). Male mesotarsal claws very unequal, the anterior almost twice the length, and very broadened, compared to posterior (Figure 6 e–f). Penis long and slender, apically upturning in lateral view, in dorsal view with the apex curved to the left and sharply pointed (Figure 7 e–f). Parameres with dorsal edge straight (Figure 7i). 11.6-13.0 mm long.

Description.

Size:ML, 11.6-13.0 mm; MW, 6.2-7.0 mm; Lp,1.2-1.6 mm; Wp, 4.7-5.3 mm; Le, 9.3-10.1 mm (n = 12).

Head. Testaceous with black areas inside and posterior of eyes. Interocular black pattern often rather broadly separated medially (Figure 2d). Dense micropunctuation but no reticulation.

Pronotum. Somewhat infuscated and with one wide dark spot which is not medially divided (Figure 2d). No rim at lateral margin. Micropunctation and vague microreticulation (Figure 3g).

Elytra. Testaceous ferrugineous with black irrorations, leaving paler sides and yellow sutural lines (Figure 2d). Black irrorations regular throughout, even posteriorly with no sign of preapical black areas. Microreticulation double, meshes are well impressed posteriorly but vague anteriorly. Micropunctation within and at edges of meshes (Figure 3 h–i).

Ventral side. Dark brown to black. Epiplura testaceous. Metafemur infuscated (Figure 4c).

Male. Protarsal claws long and slender, almost twice the length of last tarsal segment, somewhat sinuated and unequal, anterior claw longer (Figure 5 e–f). Mesotarsal claws curved and unequal, the anterior claw is almost twice as long as the posterior and much broader (Figure 6 e–f). Penis long and slender, apically upturning in lateral view, in dorsal view with the apex curved to the left and sharply pointed (Figure 7 e–f). Parameres with dorsal edge straight (Figure 7i).

Remarks.

The interpretation of Fairmaire’s name Colymbetes latus is unambiguous following common usage (e.g. Régimbart 1895, Guignot 1961), even though typematerial with Coquerel as collector could not be found in Fairmaire’s collection in Paris, or elsewhere. Neither Guignot (1961) nor Balke (1992b) were able to localize the holotype of Rhantus stenonychus and the validity of the name, based on a single specimen, has therefore not been evaluated before but the name lingered in the literature. The details for the type in Régimbart’s original description are as follows: "Madagascar: Lac Ambodinandohalo (R. P. Camboué), un seul male (coll. R. Oberthür)”. In Régimbart’s collection at MNHN there was a pin without a specimen but with the handwritten labels by Régimbart "stenonychus Rég.” and "Madag. Coll. Oberthür”. We interpret the pin with the label as a reference to the Oberthür collection for the unique type. In Oberthür’s collection a single male specimen was found bearing the label "Lac Ambodo [or Ambod°], R.P. Camboue". We believe "Lac Ambodo [or Ambod°]," is an abbreviation for Lac Ambodinandohalo and that this is the holotype. We are not able to find any records of another lake named “Ambodo” in Madagascar. Lake Ambodinandohalo was a lake in the haute-ville in Antananarivo and the French Jesuit priest and missionary Paul Camboué lived just west of Antananarivo in Arivonimamo and Ambohibeloma. Peltodytes quadratus Régimbart, 1895 was described in the same article from the same locality (Lac Ambodinandohalo, collected by R. P. Camboué) and the type specimen in Paris bore a label with the same abbreviated locality name (see Vondel 2010; Vondel and Bergsten 2012).

The holotype is as judged by morphological characters conspecific with Rhantus latus . Already in the original description similarities with Rhantus latus are obvious (also see Guignot 1961) and it is odd that Régimbart did not compare the species with Rhantus latus in his original description. We therefore synonymize the name Rhantus stenonychus with Rhantus latus .

Habitat.

Occurs in a quite wide range of habitats, like streams and rivers, muddy waterpools and grassy ponds. Of the three Rhantus species it is the only one that can be found below 1000 m altitude and known range include 530 to 2070 m.

Distribution.

Possibly endemic to Madagascar as we have not been able to verify the records from mainland Africa by Régimbart (1895) "Cafrerie, Cap" and by Guignot (1961) "Sud d’Afrique”. In Madagascar rather widespread over the central high plateau (Figure 8). Known from Andasibe-Mantadia NP, Antananarivo and Ambohijanahary NP, which are the northernmost records. Further known from several localities south of Antananarivo along RN7 from Manjakatompo forestry station to Andringitra NP, and further southwest to Isalo NP and Zombitse-Vohibasia NP. Seemingly lacking from the northern third of Madagascar.