Otumba dengi Cadena-Castañeda & Tavares, 2025

Cadena-Castañeda, Oscar J., Quintana-Arias, Ronald Fernando, Infante, Ivette Coque, Silva, Daniela Santos Martins & Tavares, Gustavo Costa, 2025, Studies on pygmy grasshoppers: On the current Metrodorinae sensu lato classification (Orthoptera: Tetrigidae) with emphasis on American and Malagasy taxa, Zootaxa 5597 (1), pp. 1-265 : 159-164

Otumba dengi Cadena-Castañeda & Tavares , sp. nov.

( Figs. 107–110 , Maps 4 and 7)

Type material. Holotype. Male. COSTA RICA, Puntarenas, District of Golfito, Guaycará, La Gamba Biological Station . 8°42’2.49”N, 83°12’7.79”W. 80 m. April 2018. F. Etl. ( CAUD) . Paratypes. 8 males, 1 female and 5 immatures, same data as holotype ( CAUD) .

Description. Male. Small-size (8.5–9.0 mm) and slender ( Fig. 107 ). Coloration. Head black, including the clypeus and labrum, with palpi outlined in brown; ocelli, scape, and pedicel ocher ( Fig. 108A ). Legs light brown; fore and mid tibiae with two black rings in the middle section; ventral external area of hind femur black, the rest light brown ( Fig. 107A ); hind tibia blurred black with a brown surface; tarsomeres with alternating coloration between black and yellowish-brown. Pronotum black, except for the yellowish distal section of the pronotal disc, and the lateral lobes with an ocher stripe running parallel to the extra lateral carina and merging into the lateral spine ( Figs. 107B , 208C). Thorax and abdomen black with few light brown spots. Head taller than wide, eyes occupying a quarter of the cephalic capsule; space between the eyes as wide as the width of one eye; lateral carinae slightly surpassing the medial carina; eyes globose, slightly protruding above the lateral carina; scutellum narrow ( Fig. 108A ); fascial carinae little diverging at the middle of the eyes, protruding in lateral view and rounded ( Fig. 108B ); lateral ocelli rounded, located near the fork of the frontal costa, a little above the lower margin of the eyes ( Fig. 108A ). Antennae with 14 segments. Thorax. Anterior margin of the pronotum straight; prozonal carinae developed ( Fig. 108C ), pronotal apex acute in dorsal and lateral view ( Fig. 107B ). Median carinae subelevated; internal and external lateral carinae up curved in lateral view; infrascapular area widened ( Fig. 107A ); lower margin of lateral lobes projected to sides as a triangular and acute spine ( Figs. 107B , 108C ). Legs slender. Fore and mid femora rectangular, longer than wide, margins sub-undulated, almost straight ( Figs. 108D, E ); hind femur with the antegenicular and genicular teeth poorly developed ( Fig. 107A ); hind tibia armed with four or five small spines on each dorsal margin. Abdomen. Last tergites from the seventh to the tenth constricted, tapering towards the anterior tergites ( Fig. 108F ), with a dorsal groove extending from the epiproct to the eighth tergite in dorsal view, dividing these segments ( Fig. 108G ). Cerci conical, tapering towards the apex, with long and abundant bristles on the basal two-thirds ( Fig. 108F ); epiproct triangular, longer than wide, divided into two hexagonal basal plates at the base (separated by the dorsal groove), and distally by a subtriangular plate ( Fig. 108G ); subgenital plate slender, tapering towards the apex in lateral view, and distally truncated ( Fig. 108F ); in dorsal view divided into the two paleal plates, sclerotized and smooth, distally ending in a point ( Fig. 108G ); in ventral view lanceolate and without modifications: penultimate sternite longer and wider than the subgenital plate both in lateral and ventral views ( Fig. 108H ).

Female. Similar to the male ( Figs. 109A, B ), differing by the ambisexual characteristics: eighth to tenth tergites with a conspicuous groove extending to the middle of the epiproct ( Fig. 109C ); cerci conical, covered with long bristles (more abundant and conspicuous than in males) ( Fig. 109D ); epiproct lanceolate, divided into three plates, two lateral rectangular (separated by the conspicuous dorsal groove), third plate subtriangular with rounded apex ( Fig. 109C ); ovipositor valves with hairs, mainly on the dorsal edges ( Fig. 109D ); subgenital plate quadrangular, with a small triangular projection on the posterior margin ( Fig. 109E ).

Measurements (in mm) male / female. CFP: 8.5–9.0 / 10.5. PL: 7.0–8.0 / 9.5. PLB: 6.0–6.5 / 6.5. FF: 2.2–2.3 / 2.5. FL: 2.5–2.6 / 2.5. MFL: 2.2–2.5 / 2.5. MTL: 2.2–2.8 / 2.8. HL: 5.5–5.7 / 6.5. HW: 2.0–2.2 / 2.2. HL: 4.0–4.5 / 5.5.

Comparison. O. dengi sp. nov. with atrophied wings, unlike the other known species with well-developed tegmina and hind wings ( Fig. 110D ). This new species could be superficially confused with O. aciculata once it also has a spine-like projection on the lower margin of the lateral lobes of the pronotum ( Figs. 110A, B ). This characteristic is also shared with O. dentata ( Figs. 101B , 102B ). Among these characters is the shape of the upper section of the head and the width of the vertex, which is more similar to South American species. In contrast, the shape of the head of O. aciculata and its overall morphology are more akin to species from the Chocó biogeographic region ( Fig. 98B , 99B ). According to Hebard (1924a), this species is very similar to O. quadrata but with pronotal spines. It also has a coloration pattern similar to O. dentata , albeit in black tones.

Remarks. Some studied males have the ocher stripe outlining the anterior margin of the lateral lobes of the pronotum, while others only have the spine of the lateral lobe delineated ( Figs. 110A, B ). Additionally, the face can be black or have a whitish surface ( Fig. 110C ). O. dengi sp. nov., despite having spines on the lateral lobes of the pronotum, also has another peculiarity: it is the only known species in the genus with atrophied wings ( Fig. 110D ). This characteristic can indeed vary within different forms of the same species, especially in Tetrigidae . However, to date, no wingless Otumba specimens have been recorded. In the records of the new species, there are no specimens with wings, and based on the studied material, it is unusual to find metrodorines with winged or wingless forms. This phenomenon is more common in other groups of Tetrigidae , such as Tetriginae and some Batrachideinae , for instance ( Rehn & Grant 1955, Berggren et al. 2012; Silva et al. 2021).

It is evident the existence of two species groups in this genus, of which O. dengi sp. nov. is located in the amazonica species group, being the only member from Mesoamerica, while the others are from South America, being more closely related to O. marcapata than the other species. The spine projection on the lateral lobes of the pronotum appears to be convergent, observed in species not so closely related, as shown here, and in taxa of American metrodorines. Some Plesiotettix , Chiriquia , and Bolivaridora gen. nov. species, have a similar spine structure.

Costa Rican records of O. dengi sp. nov. were identified as O. aciculata (https://www.inaturalist.org/ observations/74669488) and O. dentata (https://www.inaturalist.org/observations/48552702), in the catalog of Central American Tetrigidae (Kasalo et al., 2023b) . Hence, for the time being, the presence of O. aciculata in Costa Rica is ruled out, and only the type series of this species from Porto Bello, Colón, Panama is known (Hebard, 1924).

Etymology. Dedicated to Wei-An Deng, in recognition of his contributions to knowledge of Chinese Tetrigidae .

MAP 7. Distribution of Otumbini trib. nov. species.

Figures

FIGURE 98. Otumba aciculata Hebard, 1924. Male paratype. A. Habitus in lateral and, B. Dorsal view. C. Frons. D. Labels. Photos: J. Tumbrinck.

FIGURE 99. Otumba aciculata Hebard, 1924. Female paratype.A. Habitus in lateral and, B. Dorsal view. C. Frons. D. Labels. Photos: J. Tumbrinck.

FIGURE 101. Otumba dentata Hancock, 1907. Male habitus. A. Lateral and, C. Dorsal view. Photos. J. Tumbrinck.

FIGURE 102. Otumba dentata Hancock, 1907. Female. A. Habitus in lateral view. B. Habitus in dorsal view. C. Frons. D. Labels. Photos: J. Tumbrinck.

FIGURE 107. Otumba dengi Cadena-Castañeda & Tavares sp. nov. Male holotype habitus. A. Lateral view and, B. Dorsal view.

FIGURE 108. Otumba dengi Cadena-Castañeda & Tavares sp. nov. Male holotype. A. Frons. B–C. Head and thorax in lateral and dorsal views respectively. D. Fore femur. E. Mid femur. F–H. Terminalia in lateral, dorsal and ventral views respectively.

FIGURE 109. Otumba dengi Cadena-Castañeda & Tavares sp. nov. Female paratype. A. Habitus in lateral and, B. Dorsal view. C–E. Terminalia in axial, lateral and ventral views respectively.

FIGURE 110. Otumba dengi Cadena-Castañeda & Tavares sp. nov. Male paratype.A. Habitus in lateral and, B. Dorsal view. C. Frons. D. Squamiferous wings. E–F. Terminalia in lateral and dorsal views respectively.