Gymnoscirtetes Scudder 1987

Hill, JoVonn G., 2022, Revision of Gymnoscirtetes (Orthoptera, Acrididae, Melanoplinae): a genus endemic to the grasslands of the southeastern North American Coastal Plain, ZooKeys 1134, pp. 101-127 : 101

Gymnoscirtetes Scudder 1987

Gymnoscirtetes Scudder, S.H. 1897. Proc. U.S. Nation. Mus. 20 (1124): 14

External morphology.

Species of small size (M: 11.8-17 mm, F: 17.5-22.2 mm). Body somewhat gracile and subcylindrical. Head slightly wider than pronotum; hypognathous with anterior margin of head steeply declivent; triangular dorsally. Fastigium broadening apically, and broadly concave. Eyes somewhat prominent, especially in males, and thinly separated by the narrow end of the fastigium. Antennae filiform, usually with 20-23 flagellomeres in males and 21-25 in females, but often 23-26; longer than the head and pronotum combined. Thorax with prosternal spine thin and subconical. Pronotum cylindrical, anterior margin sub-truncate, often somewhat emarginated, lateral margins parallel throughout, median carina either slightly indicated or obsolete, lateral carinae obsolete. Prozona 3-4 × as long as the metazona, anterior and median sulci present laterally but indistinct near the margins; prozona smooth and shiny. Metazona mostly smooth, but with occasional reticulations, posterior margin subtruncate. Lateral lobes of the pronotum declivent anteriorly and truncate posteriorly, the ventral posterior margin obtusely angulate. Wings vestigial, minute, scale-like. Metathoracic femur slender. Metathoracic tibia with 8-10 pairs of spines. Tympanal organ greatly reduced, appearing as a small depression or slit. Terminalia with furcula (males) (Fig. 1 ) rounded protuberances, projecting either slightly or moderately beyond the end of the segment from which they originate; bases minutely separated. Supra-anal plate (Fig. 1 ) triangular, slightly longer than wide, with the median groove anteriorly distinct with elevated sides, and diverging and becoming less distinct posteriorly. Cerci (Fig. 1 ) either short, triangular, tapering from base to apex or longer and subfalcate. Subgenital plate of male with a median tubercule (Fig. 1 ).

Phallic structures.

The dorsal valves are translucent to semi-translucent lobes that are flat, truncate, shortened to elongate depending on the species. The ventral valves are opaque and more strongly sclerotized than the dorsal valves, caudally projecting cylindrical lobes of various shapes depending on the species (Figs 1 , 3 , 4 ). The aedeagal sheath only covers the base of the valves (Fig. 2 ). The epiphallus is of the typical melanoploid shape, with lophi, ancorae, and an undivided bridge. But more precisely, the epiphallus of Gymnoscirtetes has a concave bridge, broadly rounded or arched lophi, convexly curved lateral plates that are sub-rectangular in shape with an angular anterior lobe and a short, rounded caudal tip, and ancora that are triangular, taper to a point, and are decurved ventrally.

Coloration.

Overall dull greenish brown to yellow, sometimes with bronze highlights. Antenna yellowish basally, remainder ferruginous. Antennal crescent complete. Head, thorax, and abdomen pale yellow, infuscated dorsally, especially along the midline. A lateral, well-defined, piceous, post-ocular stripe extends from the caudal margin of the eye through the thorax and towards the end of the abdomen; lateral area of head and thorax below post-ocular stripe creamy-yellow. Hind femora luteous. Hind tibia, pale dull green, often dulled basally; with black or black tipped spines (Figs 1 , 4 - 9K ).

Etymology.

Gymno, Greek, naked (in reference to the seemingly apterous condition); skirtetes, Greek, leaper.

Suggested common name.

Naked leapers.

Gymnoscirtetes morsei group

Diagnosis. Typical of the genus but with male cerci generally falcate, subgenital plate with lateral lobes expanded dorsally, and central tubercle that is longer than wide (Fig. 3A-D ). Ventral valves of aedeagus more translucent and not cylindrical in shape (Figs 4A, B , 6 , 7C-G ).

Figures

Figure 1. Habitus drawings of Gymnoscirtetes A male B female.

Figure 2. Geographic distribution of Gymnoscirtetes.

Figure 3. Dorsal and lateral SEM of Gymnoscirtetes male terminalia A G. morsei (dorsal) B G. morsei (lateral) C G. rex (dorsal) D G. rex (lateral) E G. pusillus (dorsal) F G. pusillus (lateral). Note: G. pageae, G. wadeorum, and G. georgiaensis are similar to G. pusillus.

Figure 4. Partial silhouettes of Gymnoscirtetes male terminalia: A subgenital plate in caudal view B cerci in lateral view. Note: G. pageae, G. wadeorum, and G. georgiaensis are similar to G. pusillus. Within species groups there may be overlap in the shape of the cerci, and the shape is highly dependent on angle of view. Those pictured here are drawn from single individuals.

Figure 6. Gymnoscirtetes morsei: A dorsal view of male terminalia B lateral view of male terminalia C dorsal view of phallic complex D lateral view of phallic complex E dorsal view of aedeagus F lateral view of aedeagus G caudal view of the aedeagus H dorsal view of epiphallus I caudal view of epiphallus J habitus.

Figure 7. Gymnoscirtetes rex: A dorsal view of male terminalia B lateral view of male terminalia C dorsal view of phallic complex D lateral view of phallic complex E dorsal view of aedeagus F lateral view of aedeagus G caudal view of the aedeagus H dorsal view of epiphallus I caudal view of epiphallus J habitus.

Figure 9. Gymnoscirtetes pageae: A dorsal view of male terminalia B lateral view of male terminalia C dorsal view of phallic complex D lateral view of phallic complex E dorsal view of aedeagus F lateral view of aedeagus G caudal view of the aedeagus H dorsal view of epiphallus I caudal view of epiphallus J habitus.