Bioacoustics of Mellogryllus

Description. Body small ( 9–12 mm .), color dark brown with yellowish-brown legs, body surface generally smooth and shiny ( Figs. 1A–B ; 4A–B ), with bristles on edges of legs ( Figs. 2E–F, J–L ; 5B–C; G–I ), pronotum ( Fig 2C ), sternum ( Figs. 2D ; 5D ), and abdomen ( Figs. 2H–I ; 5E–F ). Head as wide as pronotum, rounded and smooth ( Fig. 1A ; 2C ; 4A ); almost as wide as high in frontal view, with epistomal suture straight ( Fig. 2A ). Vertex rounded ( Fig. 2B ). Eyes ovoid, not protruding ( Figs. 2A–B ). Lateral ocelli circular, central ocellus absent ( Fig. 2A ). Eyes and antennal pits located very low on the face, close to epistomal suture, almost at the same level ( Fig. 2A ). Fastigium wide, almost three times as wide as scape ( Fig. 2C ). Maxillary palpi mid-sized, first and second subequal in size and cylindrical; third as long as the first and second together; fourth slightly smaller than the third, with inflated ventral margin; and fifth dilated at the apex and subcylindrical ( Fig. 2B ). Thorax. Pronotal disc wider than long, covered by few and short bristles; anterior margin concave and broader than the posterior margin, with long bristles ( Figs. 1A ; 2B ; 4A ); lateral lobules square, wider than high and with a rounded lateral edge, ventral margin almost straight ( Figs. 1B , 4B ). Prosternum unarmed, triangular-shaped, with the posterior margin constricted; mesosternum quadrangular with posterior margin forming two wide and rounded-angled lobes; metasternum broader than mesosternum, slightly expanded and pentagonal, posterior margin convex ( Figs. 2G ; 5D ). Meso- and metanotum without glandular pits; mesonotum less sclerotized than metanotum. Wings. Tegmina reduced, scale-like, without distinctive venation or stridulatory area ( Figs. 1A ; 2C–D ); hind wings absent. Legs. Femora without spines; fore tibia with tympanum ovoid and elongated, only on the outer side in females ( Fig. 5C ), males without tympana ( Fig. 2F ); forelegs fossorial type , with the distal portion of the tibia and first tarsomere expanded, these with outer surfaces bearing conspicuous and strong setae ( Figs. 2F ; 5C ). Fore tibia apex with two inner spurs (inner dorsal spur is the longest) ( Figs. 2E ; 5B ) and one outer spur ( Fig. 2F ); mid-tibia with two apical spurs similar in size on each side; hind tibia with four or three spurs on each dorsal margin, and three spurs at the apex on both sides ( Figs. 2J–L ; 5G–I ). First tarsomeres with two rows of strong dorsal spines increasing in size toward the apex ( Figs. 2J–L ; 5G–I ). Abdomen cylindrical; tergites with few short bristles ( Figs. 1A–B ; 4A–B ); epiproctus subtriangular, apex rounded ( Fig. 2H ); subgenital plate short, longer than wide, apex rounded ( Fig. 2I ). Male genitalia ( Fig. 3 ). MLPs with a notch in the posterior border, without a median lobe; Ps. P. flattened dorsoventrally, not exceeding the MLPs ; Ps. a. short and not connected to rami. Ec. f. undivided, with pointed apex and very short, not extending through the MLPs ; Ec. s. well-developed and divergent. R. sclerotized with apexes acuminated and convergent, very close to each other. Arc. developed and moderately elevated in lateral view. En. c. submembranous and moderately spaced. Female. Similar to male, with even smaller tegmina ( Fig. 5A ) and tympana on the outer margin of the fore tibia ( Figs. 5B–C ). Tenth tergirte similar to male ( Fig. 5E ),.subgenital plate trapezoid ( Fig. 5F ). Ovipositor as long as the hind femur, almost straight ( Figs. 5J–K ).

Etymology. This genus is dedicated to the famous Brazilian orthopterologist Francisco Assis Ganeo de Mello in recognition of his outstanding contributions to the study of crickets. Comparison. Mellogryllus n. gen. is more similar to Kazuemba in terms of external morphology. Both genera are similar in their small size, short wings, and lack of the stridulatory area of the tegmina. However, Kazuemba differs from the new genus because, in both sexes, the tympana are absent, the tegmina have linear venation, and the genitalia resembles the typical structure of Miogryllus , sharing with this genus, the location and structure of the pseudepiphallic paramere and the divided ectophallic fold, which extends through the pseudepiphallic median lophi ( Mello 1990 ). On the other hand, Mellogryllus n. gen. has tympana on the outer face of the fore tibia at least in females, the tegmina are even more reduced, scale-like, with no apparent venation, and ectophallic fold is unusually undivided, very reduced, and do not extend through the pseudepiphallic median lophi, being the only genus of the Miogryllae group with this condition. The new genus has similarities in genital structure to Gryllita , the pseudoepiphalic sclerite with a moderately deep notch, the lateral lobes are not noticeably separated, and the ectophallic sclerites diverge, with rounded apex, not pointed. However, Mellogryllus n. gen. differs markedly from Gryllita in its external morphology since the new genus has no stridulatory apparatus in the tegmina (present in Gryllita ), small size (medium to large size in Gryllita ), and no megacephalization condition (present in several Gryllita species ). Regarding the male genitalia, Mellogryllus n. gen. can be easily distinguished by the unique condition of the ectophallic fold mentioned before.