Progomphus kimminsi Belle, 1973

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 : 249-253

Progomphus kimminsi Belle, 1973 ( Figs. 7–9 )

Reared material. ARGENTINA: 2 pharate males (molt not completed) from Santiago del Estero, Dique Los Quiroga, río Dulce , 27.66035° S, 64.36313° W, 200 m, 4/Apr/2022, Molineri, Rodríguez, Leiva leg.

Other material. ARGENTINA: 1 larva (IBN-O-105) from Jujuy, río Zora, Caimancito , 23.77222° S, 64.6125° W, 385 m, 7/Aug/2014, J. Rodríguez leg. ; 1 (IBN-O-104) larva from Salta, Guachipas, río Grande del Sauce, 25.91972° S, 65.48228° W, 1410 m, 15/9/1998, C. Molineri leg. ; 1 larva (IBN-O-106) from Tucumán, Simoca, Monteagudo, Puente RN 157, río Chico , 27.52236° S, 65.26791° S, 307 m, 13/Oct/2016, G. Hankel & E. Pero leg. ; 1 larva (IBN-O-102) from Tucumán, El Boyero, arroyo Pozo del Pescado , 26.18948° S, 65.28417° S, 784 m, 17/Dec/2016 ; 5 larvae (IBN-O-101) from Jujuy, Caimancito, río San Francisco (bajo puente de Aguas Calientes ), 23.71166° S, 64.53444° W, 360 m, 17/Nov/2014, E. Domínguez & C. Molineri leg. BOLIVIA: 1 larva (IBN-O-103) from O´Connor, Tarija, 21.77458° S, 64.09005° S, 1000 m, 6/Oct/2004, C. Molineri & V. Manzo leg.

Last instar larva. General coloration yellowish light brown ( Fig. 9a ); body tapering caudally, most of the dorsal abdominal protuberances vestigial or reduced ( Figs. 9a, d ). Head wider than long, narrower than thorax and abdomen ( Fig. 9a–b ), cephalic lobes well developed, bulging, with abundant long, stiff setae on posterior borders, occipital margin slightly concave; genae projected and covered with setae; postclypeus and frons with abundant bristle-like setae directed backwards; interocellar area and occiput smooth. Antennae four-segmented ( Fig. 9b ), scape and pedicel short and globose, third segment (the longest) slightly flattened dorso-ventrally and with a concave ventral area on basal half, densely covered with bristle-like setae, fourth segment elongate, cylindrical, with rounded tip and mostly bare; size proportion of antennomeres (1 to 4): 0.19, 0.15, 1.00, 0.40. Mandibles ( Fig. 7a–b, e–f ) with a molar crest set in a soft, fleshy area, with the following formula: L 1 2 3 4 0 a (m 1,2,3) b, R 1 2 3 4 y a (m 1,2) b; molar crest in right mandible greatly reduced. Hypopharynx subtriangular, as wide as long with few stiff setae apically and ventrally. Galeolacinia ( Fig. 7c–d ) with four ventral teeth, the apical one the longest and stoutest, two ventral teeth short and robust and a third very reduced tooth (about 1/6 length of the second, Fig. 7c ); the three dorsal teeth slender; palp as long as galeolacinia triangular and curved ( Fig. 7d ) covered with stiff setae on lateral and ventral surfaces. Labium: Prementum—postmentum articulation reaching posterior margin of procoxae; prementum subtriangular ( Fig. 7h ), ratio length/maximum width 1.3, sides slightly convex and divergent apically, with a row of thin spines ( Fig. 7h ); dorsal surface of prementum with scattered long setae. Ligula prominent ( Fig. 7g ), widely convex, fringed with two rows of 20–22 flat rounded setae. Palp subrectangular with tongue-like distal projection 1/3 length of movable hook ( Fig. 7h ), inner margin smooth, outer margin bare; movable hook long and slender, 1.2 times the length of outer margin of palpal segment. Ventral surface of prementum with a submedian pair of long hair-like setae at base of ligula, and a few setae at base; dorsal surface with scattered setae. Thorax. Pronotum U-shaped, wider than long, with anterior v-shaped furrow, submedian plate slightly elevated, anterolateral corners bulging and covered with thin setae ( Fig. 9a–b ). Meso- and metathorax bare except along lateral margins. Wing pads strongly divergent, anterior wing pads almost reaching posterior margin of S4, posterior ones reaching anterior margin of S5. Legs short and thick; pro- and mesotibiae without burrowing hooks and with a subbasal dorsal swelling densely covered with thick seta, pro- and mesotarsal claws cheliform, metatarsal claws long and acute with a subapical seta; pro- and mesotarsi flattened. Abdomen ( Figs. 8a–c ) slightly widening to its maximum at S5 and S6, then gradually tapering, setose on lateral margins ( Fig. 9a ). Terga granulose and with short setae, with darker marks near anterior margin of terga S4–7 (a larger median subtriangular mark and a smaller circular submedian mark); near posterior margin with a sublateral circular mark and a larger mark on porterolateral corners; the posterior marks on terga S7–10 tend to fuse ( Fig. 9a ). S4–9 with well-developed sharp posterolateral spines increasing in length rearward, those on S6–8 subequal and longest ( Fig. 8c ). Dorsal tubercles ( Fig. 9c ) small, thin and pointed, present on S1 to S3 only ( Figs. 8a–b , 9c ). Sterna glabrous, brown, darkening toward rear segments, sternum S9 with a row of long thin setae near anterior margin; sterna S2–9 composed of three plates, S1 and S10 composed of one plate. Proportionate lengths of sternum S8: S9: S10: epiproct (n=3) = 2.1: 1.75: 1: 2.8. Male gonapophyses absent. Female gonapophyses rudimentary and rounded, mostly hidden on posterior margin of sternum 8. Caudal appendages pale except base brownish, acutely pointed and fringed with long stiff setae, epiproct and paraprocts granulose; cerci triangular ( Figs. 9e–g ). Size proportion of caudal appendages, cerci: epiproct: paraprocts = 0.37: 1.0: 1.06; epiproct and paraprocts as long as sterna S9–10 combined. Paraprocts with the ventral inner margin strongly concave on the basal half ( Fig. 9g ).

Measurements (in mm, n=3): Total length excluding caudal appendages, 17.5–19.0; abdomen without caudal appendages (ventral), 11.0–12.2; maximum width of head, 3.7–3.9; hind femur (lateral), 2.3; lateral spine on S8 (ventral, on inner margin), 0.25–0.30; epiprocts (dorsal), 1.70–1.85; paraprocts (dorsal), 1.80–1.90; cerci (dorsal), 0.7–0.8.

Larval diagnosis. Progomphus kimminsi can be distinguished from the larva of other species in the genus by the following combination of characters: fourth antennomere relatively long and slender ( Fig. 9b ); mandibular formula ( Figs. 7a–b ): L 1 2 3 4 0 a (m 1,2,3) b, R 1 2 3 4 y a (m 1,2) b; galeolacinia with 4 ventral teeth, the first one (basal) very reduced, about 1/6 length of the second ( Fig. 7c ), maxillary palp tapering apically ( Fig. 7d ); prementum ( Fig. 7h ) subtriangular, lateral margins with a row of thin spines, dorsal surface with scattered long setae; ligula prominent with two rows of flat slender and apically rounded setae ( Fig. 7g ); palp with tongue-like distal projection 1/3 length of movable hook, margins smooth; movable hook long and slender, slightly longer than outer palpal margin; proand mesotarsal claws cheliform, hind tarsal claws normal with a subapical seta; thorax and legs with whitish setae; pro- and mesotibia without distal spurs; hind tarsi darker than the rest; posterolateral spines present on S4–9 ( Fig. 8c ); small dorsal tubercles present on terga S1–3 ( Figs. 8a–b , 9c ); sterna S2–9 formed by 3 plates; apical abdominal segments and anal pyramid slender, relative length of sternum S8: S9: S10: epiproct = 2.1: 1.75: 1: 2.8.

The larval stage of P. kimminsi is similar, among Argentinean species, to P. aberrans and P. complicatus (see discussion of characters under P. aberrans ). Unique characteristics of the larva of P. kimminsi include the reduction of the number of dorsal abdominal tubercles, which are present only on S1–3 (at least on S 2–9 in the remaining species), and posterolateral spines present on S4–9.

Distribution. Argentina (Jujuy, Salta and Tucumán, and new provincial record for Santiago del Estero) ( Belle, 1973; Lozano et al. 2020). New records for Bolivia (mentioned as present in von Ellenrieder & Garrison 2007, but without detailed material).

Notes. The site where the reared material was collected is intensely used for recreational purposes, mainly for bathing resort and fishing. Heterogeneity of fluvial habitat is represented by rocky areas formed by clay agglomerates with abundant cobbles, pebbles and gravel; areas of sand dunes with depositional banks, on which shrub vegetation can develop; and lateral lagoons with abundance of floating macrophytes during the low water period. Channel width is approximately 400 m, but wet width is around 200 m most of the year, with average depth of 60 cm. River bed is characterized by the prevalence of medium-grained sand, which represent 60% of the substrate, with scarce organic matter content (<1%). Waters are alkaline, with pH average of 8.3 (+0.5), mean temperature of 20.8°C (+3.1), electrical conductivity of 728.7 µS.cm-1 (+139.2), dissolved oxygen of 9.1 mg.L-1 (+0.8), alkalinity 171 mg.L-1 CaCO 3, and hardness 148 mg.L-1 CaCO 3. In benthic macroinvertebrate assemblages Chironomidae and Oligochaeta are dominant ( Leiva et al. 2020).

Figures

FIGURE 7. P. kimminsi Belle, last instar larval exuvia: a, left mandible with detail, occlusal view; b, right mandible with detail, occlusal view; c, maxilla, ventral view (arrow indicates first tooth); d, same, dorsal view; e, left mandible, ventral view; f, right mandible, ventral view; g, ligula. detail of flat marginal setae; h, prementum, ventral view.

FIGURE 8. P. kimminsi Belle, last instar larval exuvia: a, lateral abdominal outline, detail of tubercles on segments 1–3; b, lateral abdominal outline; c, ventral abdominal outline (arrow indicate spine present on S4).

FIGURE 9. P. kimminsi Belle, last instar larval exuvia: a, dorsal habitus; b, detail of head, dorsal; c, detail of abdominal dorsal hooks (arrows); d, abdomen, lateral; e, anal pyramid, dorsal; f, same, lateral; g, same, ventral.