Progomphus phyllochromus Ris, 1918

Molineri, Carlos, Rodríguez, José Sebastián, Leiva, Marta & Márquez, Javier Andrés, 2023, Diagnoses and key for the larvae of Progomphus Selys, 1854 from Argentina (Anisoptera: Gomphidae), with first larval descriptions for P. aberrans Belle, 1973 and P. kimminsi Belle, 1973, Zootaxa 5297 (2), pp. 239-259 : 255-258

Progomphus phyllochromus Ris, 1918 ( Figs. 12–13 )

Reared material. ARGENTINA: 2 male and 1 female adults with associated larval exuviae (IBN-O-67, 68, 69) from Salta, Metán, río Las Conchas , 25.47611° S, 64.97666° W, 890 m, 17/Dec/2016, C. Molineri & J. Rodríguez leg. ; 3 male and 3 female adults with associated larval exuviae (IBN-O-70, 72, 74, 77, 78, 80) from Tucumán, Burruyacú, Villa Padre Monti, Segunda cascada, 26.49981° S, 64.99804° W, 930 m, 30/Dec/2017, C. Molineri & J. Rodríguez leg. ; 1 (larva) IBN-O-238, same data; 3 larvae (IBN-O-73) same data; 1 male and 1 female adults with associated larval exuviae (IBN-O-1429, 1431) from Tucumán, Tapia, puente RN9, río Tapia , 26.61046° S, 65.26338° W, 668 m, 29/Jan/2022, C. Molineri & G. Fontanarrosa leg.

Other material. ARGENTINA: 1 larva (IBN-O-117) from Tucumán, Trancas, El Boyero, arroyo Pozo del Pescado , 26.18948° S, 65.28417° W, 784 m, 17/Dec/2016, C. Molineri & J. Rodriguez leg. ; 1 larva (IBN-O-119) from Tucumán, Monteros, Pueblo Viejo, arroyo Yacuchina , 27.14083° S, 65.76805° W, 945 m, 10/Feb/2000 , Molineri et al. leg .; 1 larva (IBN-O-116) from Jujuy, Ledesma, Caimancito, río Zora , 23.77222° S, 64.61250° W, 385 m, 16/Nov/2014, E. Dominguez & C. Molineri leg. ; 3 larvae (IBN-O-118), same data except: 7/Aug/2014, J. Rodriguez leg.

Larval diagnosis. The larval stage of P. phyllochromus can be distinguished from other described larvae in the genus by the following combination of characters: fourth antennomere reduced, knob-like ( Fig. 13b ); mandibular formula: L 1234 0 a (m 1,2,3,4,5) b, R 1234 y a+b ( Figs. 12a–b ); galeolacinia with 4 ventral teeth, the first (basal) one 1/2 length of the second ( Fig. 12c ), palp thick ( Fig. 12d ); prementum subrectangular ( Figs. 12f, h ), ligula with a pair of contiguous submedian tubercles ( Fig. 12e ), margin with two rows of flat setae, both formed by slender setae, those of the ventral row less than ½ length of the dorsal setae; lateral margins of prementum bare, dorsal surface with 3 submedian setae and a grumose submedian area ( Fig. 12h ); labial palp with smooth margins, inner apical projection with sclerotized margin, tongue-like, reaching basal 1/2 of movable hook, movable hook stout slightly shorter than outer palpal margin ( Fig. 12g ); tarsal claws not cheliform, normal (long and acutely pointed, flattened), hind claw with a subapical seta; thorax and legs with whitish setae; pro- and mesotibia with distal spurs; hind tarsi light colored; posterolateral spines on S6–9 ( Fig. 13e ); blunt relatively large dorsal tubercles on terga S2–9 ( Fig. 13d ); sternum S2–9 formed by three plates, except sternum S8 formed by 5 plates ( Figs. 13e, h ); apical abdominal segments and anal pyramid stout, relative length of sternum S8: S9: S10 (1): epiproct = 1.3: 1.2: 1:1.1 (Figs. 14a, f, g).

Limongi (1983) described the larva of P. phyllochromus based on 20 exuvia of both sexes, it is not clear if the association with adult was direct or by supposition. Differences between this description and our material include the presence of small median tubercles on margin of ligula, and the group of dorsal setae on each side of the prementum, not mentioned in Limongi (1983). Mandibles and maxilla are described here for the first time and resulted useful to further diagnose the species. Among the Argentinean species, the larva of P. phyllochromus is similar to P. lepidus and P. joergenseni , see discussion under this last species for further comparisons.

Distribution. Argentina (Jujuy, Salta, Santiago, Tucumán), Bolivia, Brazil, Perú, Venezuela, Colombia and Ecuador ( Belle 1973; Pérez-Gutiérrez et al. 2011; Koroiva et al. 2020; Lozano et al. 2020).

Figures

FIGURE 12. P. phyllochromus Ris, last instar larval exuvia: a, left mandible, occlusal view; b, right mandible, occlusal view; c, maxilla, ventral view (arrow indicates first tooth); d, same, dorsal view; e, ligula. detail of flat marginal setae; f, prementum, ventral view; g, detail of labial palp, ventral view; h, prementum with detail, dorsal view.

FIGURE 13. P. phyllochromus Ris, last instar male larva: a, dorsal habitus; b, head and pronotum, dorsal (antennomeres are numbered); c, detail of tibial spurs (ts), ventral; d, abdomen, lateral; e, same, ventral; f, anal pyramid, dorsal; g, same, lateral; h, abdominal sterna S8–10 (numbers indicate plates on S8).