Rhopalosiphum chusqueae Perez Hidalgo & Villalobos Muller

Hidalgo, Nicolas Perez, Martinez-Torres, David, Collantes-Alegre, Jorge Mariano, Muller, William Villalobos & Nafria, Juan M. Nieto, 2012, A new species of Rhopalosiphum (Hemiptera, Aphididae) on Chusquea tomentosa (Poaceae, Bambusoideae) from Costa Rica, ZooKeys 166, pp. 59-73 : 63-64

Rhopalosiphum chusqueae Perez Hidalgo & Villalobos Muller sp. n.

Holotype.

Apterous viviparous female number 1 of measurement series, caught on Chusquea tomentosa , Pérez Hidalgo & Villalobos Muller leg., deposited in the Aphidological Collection of the University of León (CZULE), sample CRI-235.

Paratypes.

2 apterous viviparous females (in separated slides) caught with the holotype.

Etymology.

The specific epithet, chusqueae is the genitive singular of the generic name of the aphid’s host plant.

Apterous viviparous females

(Figure 2). When alive globular oval and brown with white spots of wax on abdomen. Mounted 2.20-2.72 mm and pale in general with head, antennae, legs, siphunculi and cauda dark-brown.

Antennae 0.63-0.79 times body length. Antennal segment III (0.32-0.43 mm) shorter than segment IV (0.21-0.25 mm) plus V (0.20-0.26 mm); with setae 55-65 μm long and 1.8-2.6 times the articular diameter of the segment. Terminal process of segment VI (0.44-0.47 mm) 3.9-4.4 times the base (0.32-0.43 mm). Rostrum 0.52-0.61 mm long, reaching middle coxae, 0.19-0.27 times the body length. Ultimate rostral segment 0.13-0.15 mm long, approximately 1.7 times its basal width and 1.1 second segment of hind tarsus; it carries two accessory setae. Marginal papillae present on prothorax, on the abdominal segment 1 and 7, which are dorsally placed to the respective spiracles, and sometimes on segments 3 and 6. Dorsum of the abdomen with spinules forming reticulate ornamentation. Dorsal setae on abdominal segment 3 with delicate, pointed and 25-30 μm long and 3.0-3.9 times the articular diameter of antennal segment III and shorter than ventral ones, which are 90-110 μm long. Siphunculi slightly swollen with marked narrowing below the flange, 0.41-0.45 mm long, 0.16-0.20 times the body length and 2.1-2.2 times cauda. Abdominal segment 8 with two sclerites and four setae 90-110 μm long, delicate and pointed. Genital plate with 2 discal setae and near 26 posterior ones. Cauda finger-like, 0.19-0.21 mm long and carrying 5 setae.

Distribution and host-plant.

Chusquea tomentosa ( Poaceae , Bambusoideae ) is the only known host of Rhopalosiphum chusqueae . This bamboo is endemic to the country and can be found in several areas of the Cordillera de Talamanca at an altitude of between 2450 and 3000 m ( Widmer 1997; Hammel et al. 2003). Species of Chusquea (approximately 120 described) can be found at between 800 and 3800 m in dry and humid forests from Mexico to Chile and Argentina ( Clark 1989). As species in the genus Rhopalosiphum are not strictly stenophagous, Rhopalosiphum chusqueae may also live on other species of Chusquea , or even on other bamboos and live in other parts of America.

On the plant, the aphids live close to the nodes well protected by the leaves (Figs 1C, 1D) and not easily detectable, as shown by fruitless efforts to locate other colonies.

So far, only one aphid species had been recorded on Chusquea : Hysteroneura setariae (Thomas) on Chusquea abietifolia Griseb, in Cuba ( Holman 1974).

Blackman and Eastop (1994) present two identification keys to the aphid species living on Arundinaria and on Bambusa , genera that include arboreal bamboos; several of these aphid species belong to the subfamily Aphidinae . Blackman and Eastop (2006) report the presence of aphid species on several genera of non-arboreal bamboos such as Chusquea , Pseudosasa , Sinoarundinaria , Thamnocalamus , Thysanolaena , and also Arundinaria (other bamboo genera are included but no Aphidinae species have been recorded on them), and for the identification of these species the reader is forwarded to the "keys [of 1994] to aphids on Arundinaria and Bambusa ", or to the "keys [of 2006] to apterae on Digitaria and other genera of herbaceous Poaceae ". To make the identification work easier, it seems useful to present one compendium-key to the identification of apterous viviparous females of Aphidinae species recorded on species of Bambusoideae in the World.

This key has been prepared using the general structure and several couplets in all of those keys by Blackman and Eastop; thirteen Aphidinae species and subspecies have been included, and are: Hysteroneura setariae (Thomas, 1878), Melanaphis arundinariae (Takahashi, 1937), Melanaphis bambusae (Fullaway, 1910), Melanaphis meghalayensis bengalensis Raychaudhuri [D.N.] and Banerjee [C.], 1974, Melanaphis meghalayensis meghalayensis Raychaudhuri [D.N.] and Banerjee [C.], 1974, Melanaphis pahanensis (Takahashi, 1950), Melanaphis sacchari (Zehntner, 1897), Rhopalosiphum arundinariae (Tissot, 1933) and Rhopalosiphum rufiabdominale (Schrank, 1899) ( Aphidinae Aphidini Rhopalosiphina ), and Sitobion bambusicola (Ghosh [L.K.], 1986), Sitobion fragariae (Walker, 1848), Sitobion miscanthi (Takahashi, 1921) and Sitobion papillatum subnudum Remaudière, 1985 ( Aphidinae Macrosiphini ).