Mnesarete guttifera (Selys, 1873)

Mendonça, Ana Julia Eugenio, Datto-Liberato, Felipe Henrique & Guillermo-Ferreira, Rhainer, 2025, Description of the last instar larva of Mnesarete guttifera (Selys, 1873) (Odonata: Calopterygidae), Zootaxa 5647 (4), pp. 395-398 : 395-397

Description of the last instar larva of Mnesarete guttifera (Selys, 1873)

Material examined. 1 ♂ and 1 ♀ (Reared) exuvia F0, Brazil, Serra da Canastra, Rio do Peixe (20°15’28”S, 46°24’36”W; São Roque de Minas, MG, Brazil), 08-09-III-18, Guillermo-Ferreira leg., ( Figs. 1–6 ).

Exuviae. Light yellow, yellow abdomen, slender and cylindrical body, with abdominal tergites marked by darker bands ( Fig. 1 ).

Head. Pentagonal, 1.38 times wider than long; concave occiput; with a pronounced latero-dorsal tubercle; rounded cephalic lobe ( Fig. 1 ).

Antenna. About 2 times longer than the length of the head and 1.5 times longer than the head and prothorax combined; the 1st antennomere is 1.37 times longer than the others combined. The antennae of the male are composed of 7 segments: measuring 2.14, 0.66, 0.38, 0.21, 0.12, 0.12, and 0.08 mm, respectively ( Fig. 2 ). The antennae of the female are missing 5 of the 7 segments: measuring the first two segments, 3.68 and 0.91, respectively.

Prementum. Triangular with a medial cleft and a prominent distal margin; projections of the fissure are united at the apex. The inner margins of the projections have two pairs of spiniform setae, while the outer margins of the projections are serrulate ( Fig. 3 ).

Labial palp. Movable hook, 1.48 times shorter than labial palp, three pairs of sharp teeth on the distal margin, the ventral one being smaller and curved; presence of three palpal setae on the lateral margin; the inner margin is irregularly serrulate ( Fig. 3 ). Mandibles formulae L 12345 0 a(m 1,2,3,4,5,6) b R 12345 y ab ( Fig. 4 ).

Thorax. The prothorax is trapezoidal with lateral angles developed into a conical projection with a rounded apex. Wing pads extend to the S4. Long, pale legs, with the hind leg exceeding the apex of the abdomen. The femora feature two dark bands, while the tibiae have three darker bands, less pronounced. The tarsi are pale, and the tarsal claw is simple ( Fig. 1 ).

Abdomen. Cylindrical, generally covered with small setae concentrated on the distal segments.

The postero-dorsal margin of S10 has a keel and a developed hook ending in 3 spines at the apex, along with two small additional spines, one on each side of the medial hook. Short lateral spines are present on S8–10 ( Fig. 1 ). The male cerci are 0.5 times the lateral length of S10, digitiform, inclined, slightly curved inward/downward ( Fig. 5 ). Female cerci are half the lateral length of S10, cylindrical, conical, gradually tapering to apex ( Fig. 6 ). The female gonapophyses does not reach the apex of S10; the apex of the external valva is cylindrical and ends in a pointed spine, and the ventral margin has several setae ending in a small spine ( Fig. 6 ). Medial caudal lamella: 3.18 times longer than wide, 1.22 times shorter than lateral lamellae, rounded apex; all caudal lamellae bear spines; lateral lamellae lanceolate and triquetral ( Fig. 7 ). There is no differential feature in the chaetotaxy of the lamellae between the dorsal and ventral series. The dorsal and ventral series of the epiproct do not show any notable differences.

Measurements (mm). Male (n=1). Total length without lamellae: 16.35. Total length of the head: 1.77; width: 2.46. Prementum length: 4.37; width: 2.32. Total length of labial palp: 1.61; width: 0.44. Femur I: 4.10; II: 4.88; III: 5.50. Tibiae I: 4.70; II: 4.90; III: 5.0. Inner wing pads: 5.25, external wing pads: 5.84, Medial caudal lamellae: 6.15; lateral caudal lamellae: 7.54.

Female (n=1). Total length without appendages: 16.50. Total length of the head: 2.07; width: 3.51. Prementum length: 4.67; width: 2.51. Total length of labial palp: 1.54; width: 0.48. Femur I: 4.28; II: 5.68; III: 6.67. Tibiae I: 5.02; II: 5.72; III: 5.89. Inner wing pads: 4.76, external wing pads: 4.63 Medial caudal lamellae: 5.97; lateral caudal lamellae: 7.41.

Taxonomic notes. The morphological similarity between species of the genera Hetaerina and Mnesarete was discussed by Garrison (2006). Standring et al. (2022) suggested Mnesarete as paraphyletic based on morphological and molecular analyses. Hence, to date, there is no morphological trait that is useful to distinguish between larvae of both genera as discussed by Anjos-Santos et al. (2018). Mnesarete guttifera can be distinguished from M. astrape , M. cuprae , and Hetaerina larvae by the smooth first antennomere, i.e., lacking spines. Additionally, the abdomen of M. guttifera is smooth and lacks tubercles. It differs from M. grisea by the mandibular formula, with the right mandible having simple molars, whereas M. grisea has a crest between molars a’ and b’. Mnesarete guttifera is also distinct from M. pudica , having 2 pairs of palpal setae compared to the 3 pairs in M. pudica , and the left mandible presents a molar crest of M. guttifera bears 6 denticles, in contrast to the 4 denticles in M. pudica . Mnesarete guttifera also presents a pair of lateral spines on S8–10 absent in M. pudica . Morphological data for these species were extracted from: Hetaerina caja ( Drury, 1773) ( Geijskes 1943) ; H. medinai Rácenis, 1968 ( De Marmels 2007); H. rosea Selys, 1853 ( Pessacq & Muzón 2004); Mnesarete grisea ( Ris, 1918) ( Garrison 2006) ; M. pudica (Hagen in Selys, 1853) Guillermo-Ferreira & Bispo 2012); M. astrape De Marmels, 1989 and M. cupraea (Selys, 1853) ( Neiss 2012) .

Figures

FIGURES 1–7. Final instar of the larva of Mnesarete guttifera (Selys, 1873): 1. Dorsal view of the exuvia of a reared male habitus; 2. Lateral view of the antenna; 3. Dorsal view of the prementum, with details of the labial palps in mid-dorsal view; 4. Dorsal view of the mandibles, with details from the left molar teeth; 5. Lateral view of S9–10 and cerci of male; 6. Lateral view of S8–10 and gonapophyses of female; 7. Lateral lamella (right) and medial lamella (left) of the male.