﻿Revision of Gymnoscirtetes (Orthoptera, Acrididae, Melanoplinae): a genus endemic to the grasslands of the southeastern North American Coastal Plain

﻿Abstract Gymnoscirtetes is endemic to the southeastern portion of the North American Coastal Plain and previously comprised two species: G.pusillus Scudder, 1897 and G.morsei Hebard, 1918. Here, this genus is revised based on male genital morphology and geographic data, and four new species are described: G.georgiaensissp. nov., G.pageaesp. nov., G.rexsp. nov., and G.wadeorumsp. nov.Gymnoscirtetes is primarily associated with mesic grasslands such as pitcher plant bogs, flatwoods, and the edges of seasonal ponds, but can be found less commonly in a variety of other grasslands.


Introduction
The North American Coastal Plain was recently designated as the world's 36 th global biodiversity hotspot based on the high levels of biodiversity and endemism of vascular plants and habitat loss greater than 70% in the region (Noss 2016). A disproportionate amount of this biodiversity is found in the imperiled grasslands of the region, though they have historically received much less attention from conservation and natural resource agencies than forests and wetlands in the region (Noss 2013;Noss et al. 2015, Body Length -Dorsally from the fastigium vertices to the distal end of the genicular lobe of caudal femur in a parallel plane with the abdomen. Pronotum length -Dorsally, along the median carina. Cercus Length -Laterally, maximum possible measurement of the left cercus. Cercus Basal Width -Laterally, along the point of attachment from the dorsal to ventral margin. Mid Cercus Width -Laterally, at the mid-length of the left cercus. Cercus Apex Width -Laterally, along the distal end. Subgential Plate Tubercule Length -Laterally, from the base to the apex. Subgential Plate Tubercule Width -Posteriorly, at the widest point.

Results
Based on male morphology and distribution, Gymnoscirtetes easily divides into two distinct species groups. The morsei group comprises two species that are western in distribution, from Mobile Bay, Alabama, to the Ocklochnee River, Florida (Fig. 12). The pusillus group comprises four species that are eastern, from the Ocklochnee River, Florida (i.e., the eastern edge of the morsei group) to east Georgia, and south towards Lake Okeechobee, Florida. Comparison with related genera Gymnoscirtetes 1. Small size (11-22 mm). 2. Body linear in shape (Fig. 1). 3. Appearing apterous with wings reduced to a minute, vestigial scale. 4. Body brownish-green or bronze with a black stripe running from behind the eye to near the end of the abdomen (Fig. 1). 5. Hind tibia and tarsi dull green. Aptenopedes 1. Large size (17-28 mm). 2. Body somewhat elongate. 3. Wings developed into small linear pads. 4. Body green or brown with white and black striping. 5. Hind tibia blue, tarsi pink. Eotettix 1. Size variable -small (10-20 mm) to larger (18-28 mm). 2. Body more robust. 3. Brachypterous but wings obvious. 4. Body green to bronze with a metallic luster; black postocular stripe. 5. Hind tibia and tarsi black or red depending on the species.     Dorsal valves of the aedeagus truncated or slightly angular apically and not expanded laterally, usually parallel sided (Figs 5E, F, 10C-G,11C-G); Florida and southern Georgia, but not the "Big Bend" region ( Fig. 12)  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 mel-anoploid 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.

Checklist of groups and species
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).
Suggested common name. Naked leapers.

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).

Diagnosis.
Most easily differentiated from the other species in the group based on the shape of the male cerci, which in G. morsei are decurved apically to an acute point ( Fig. 6A, B), and by the shape of the male genitalia which have the dorsal valves rounded apically (Fig. 6G). The tubercle of the subgenital plate is often broader in most individuals of G. morsei, especially those in the western portion of the range. Male measurements. (mm): (n = 14) Body length 13.2-17.0 (mean = 14.6); pronotum length 1.9-2.6 (mean = 2.26); hind femur length 6.1-7.9 (mean = 6.9); cerci length 1.2-1.5 (mean = 1.3); basal width of cercus 0.4-0.7 (mean = 0.6); midcercal width 0.    Distribution. Mobile Bay (Baldwin County, AL) east through the panhandle of Florida to Bay and Jackson counties (Fig. 12).
Habitat. Hebard (1918) describes the type locality at De Funiak Springs, Florida as being "a boggy area of wire-grass and bog plants, which was not more than fifteen yards wide by forty yards long". At Splinter Hill Bog, in Baldwin County, AL (Fig. 13A), G. morsei occurs in a large bog dominated by Sarracenia leucophyllia Raf. and other carnivorous plants. Diagnosis. Differs from G. morsei in having more narrow male cerci and curving or rotating medially apically, with the apex curving back laterally. In some individuals the apex of the cerci may be less acute or sometimes rounded (Fig. 7A, B). The dorsal valves of the male genitalia are truncated and decurved distally. The ventral valves are decurved and taper to a point distally (Fig. 7G). The tubercle of the subgenital plate is often narrower in most individuals of G. rex than in specimens of G. morsei.

Gymnoscirtetes rex
Male measurements.  Distribution. Occurs in a narrow portion of the eastern Florida panhandle. At present, it is known only from Bay, Calhoun, Franklin, Gulf, and Liberty counties (Fig. 12).
Etymology. From the Latin rex for monarch, in reference to the crown-like shape of the subgenital plate. The inspiration for this name came one day while at a local coffee shop (929) that had a crown as part of their logo. The shop was selling crown-shaped cookies by the cash register. I was working on this revision at the time and the shape of the cookies instantly remined me of the shape of the subgenital plate of this species.
Habitat. This species can be found in much drier conditions that other members of the genus. At the type locality this species inhabited fine grasses in a sandy upland with Chrysoma pauciflosculosa (Michx.) Greene (Fig. 13B). I have also collected this species from a large expanse of Quercus minima (Sarg.) Small in a sandhill. Specimen notes from other specimens indicate it inhabits bogs and savannahs as well.

pusillus group
Diagnosis. Typical of the genus, but with the male cerci triangular and subgenital plate with the lateral lobes not expanded dorsally and with the tubercule approximately as long as wide (Figs 3C, 4B). Ventral valves of the aedeagus opaque and cylindrical in shape (Figs 8-11A-G).

Gymnoscirtetes pusillus Scudder, 1897
Figs 3E, F, 4B, 5C, 8A-J, 12, 14G Gymnoscirtetes pusillus Scudder, 1897: 15 Diagnosis. Differs from other species in the group based the shape of the internal male genitalia. In dorsal view, the dorsal valves are lightly sclerotized and semi-translucent, have apices that are rounded to sub-truncate, and shorter than the ventral valves (Fig. 8C, E). In lateral view, the dorsal valves taper to their apices and the ventral valves extend slightly past the dorsal valves with apices that are rounded to slightly angular (Fig. 8B, D, G).
Type information.  Gymnoscirtetes pageae sp. nov. https://zoobank.org/3F1242B8-CF10-4AFE-89DD-7DA9E0ECD0F2 Figs 5D, 9A-J, 12, 14D, G Diagnosis. Differing from other species in the group based on the shape of the internal male genitalia (Fig. 9C-I). In dorsal view, the dorsal valves form two slightly translucent lobes that are equal to or are slightly longer than the ventral valves and are truncated apically. The ventral valves are opaque short cylindrical protrusions that are rounded at their apices. In lateral view, the dorsal valves are much broader than the ventral valves (~ 1.5 ×) and extend laterally up to or just short of the apex of the ventral valves. In caudal view, the dorsal valves form a girdle that almost completely encompasses the ventral valves like a hood (Fig. 9G). This species is perhaps the most distinct in the group and can readily be identified based on its unique genitalia and distinct geographic distribution (Fig. 12).
Holotype Distribution. "Big Bend" region of Florida from Leon and Wakulla counties, south through the flatwoods to the western banks of the Suwannee River in Dixie County (Fig. 12).
Habitat. Flatwoods and grassy sandhills (Fig. 13D). Etymology. Named in honor of Bettie Mae Page, an iconic American photo model and former resident of Florida, who rose from a background of poverty and abuse to become a symbol of self-expression and body positivity. Diagnosis. Differing from other species in the group based on the shape of the internal male genitalia (Fig. 10C-I). In dorsal view, the dorsal valves form two translucent lobes that are equal to or slightly longer than the ventral valves and are truncated apically. The ventral valves are opaque short cylindrical protrusions that are rounded at their apices. In lateral view, the dorsal valves are broader than the ventral valves and taper to their apices. In caudal view, the dorsal valves extend above the ventral valves (Fig. 10G). This species is very similar to G. pusillus but is distinguished from that species by the length and angle of the dorsal valves which are longer and are angled more dorsally in G. wadeorum, and their separate geographic distributions (Fig. 12).
Distribution. Found in southern Georgia and north Florida, from Berrien County, GA west to the Chattahoochee River, and south to Liberty and Baker Counties, FL (Figs 12, 13C).
Habitat. Flatwoods and pitcher plant bogs. I observed this species feeding on Seymeria cassioides (J.F.Gmelin) S.F.Blake at Doerun pitcher plant bog.
Etymology. Named in honor of the Wade Family who, in 1979, placed an 85-ha tract of old growth longleaf pine savanna into a perpetual conservation easement. Today, the "Wade Tract", is one of the most important remaining examples of the long leaf pine ecosystem in existence and is also the type locality of this species. Diagnosis. Differing from other species in the group based on the shape of the internal male genitalia (Fig. 11C-I). In dorsal view, the dorsal valves form two translucent lobes that are nearly equal in length to the ventral valves and are pointed at their apices. The ventral valves are opaque cylindrical protrusions that are pointed at their apices. In lateral view, the dorsal valves are nearly equal in length to the ventral valves, twist caudally and taper to their apices. In caudal view, the dorsal valves extend above the ventral valves (Fig. 11G). This species can most easily be separated from G. pusillus by having longer dorsal and more translucent dorsal valves and from G. wadeorum by the more angled apices and the slight caudal twist in the dorsal valves. G. georgiaensis can also be distinguished from these species by their separate geographic distributions (Fig. 12).
Female measurements.   Distribution. All known locations occur on the lower Coastal Plain of Georgia Bulloch County south to Ware and Charlton Counties (Fig. 12).
Habitat. Flatwoods and pitcher plant bogs.
Etymology. Named after the state of Georgia, from which this species is apparently endemic.

Discussion
The four new species of Gymnoscirtetes described here further demonstrate the high levels of endemism and undiscovered biodiversity on the North American Coastal Plain. The apparent center of diversity for Gymnoscirtetes is the area along the northeast Gulf of Mexico where four of the six species are distributed. In this region the Apalachicola and Sewanee Rivers along with the Mobile/Tensaw River delta combined with ecological changes resulting from Pleistocene glacial cycles have produced important biogeographic barriers for isolating populations and generating new species resulting in a biodiversity hotspot with numerous terrestrial taxa that show similar patterns of divergence (Sorrie and Weakly 2001;Soltis et. al. 2006;Hill 2015;Huang et al. 2020).
A complete phylogeny of the North American Melanoplinae is under way but is still several years away from completion. As such, the origins of the five NACP endemic genera remain unknown. Until this work is completed, I hypothesize that Gymnoscirtetes arose from a western ancestor that spread into southeastern North America during the Miocene or Pliocene. Gymnoscirtetes species are inhabitants of several types of (often mesic) grasslands. Ancestral species could have spread eastward during periods of drier climatic conditions that favored the spread of grassland habitats. During the Miocene, a corridor of semiarid live oak-conifer woodlands, arid subtropic scrub, grassland, subdesert to desert vegetation existed on the Gulf Coastal Corridor (Axelrod 1958;Webb 1977;Albright 1998;Noss 2013). Arid plant conditions may not seem suitable for the spread of mesic grassland inhabiting species, but even under current conditions many of the mesic grasslands inhabited by Gymnoscirtetes are adjacent to or are interspersed among scrub environments. In some cases, they occur in grasslands that are only wet for a portion of the year as is the case in the hyper-seasonal Florida dry prairies. Populations of the ancestral species could have then repeatedly isolated by advancing and retreating glaciers during the Pleistocene, which would have also created larger rivers that would have acted as biogeographic barriers. The two species groups were probably isolated early on during the Pleistocene with each group radiating later during the period, as seen in the Melanoplus scudderi group (Huang et al. 2020).
Despite being relatively secure in terms of conservation at present, Gymnoscirtetes may be of conservation concern in the future. Many co-occurring plant communities (e.g., long leaf pine savannas and pitcher plant bogs) are imperiled and have undergone drastic reduction in the last 200 years. Thus, threats to Gymnoscirtetes are habitat loss from anthropogenic habitat alterations and potential loss of habitat from climate change which may result in the flooding of their low-lying environments near the edge of the Coastal Plain. Given the growing interest in the biodiversity of the North American Coastal Plain, and the recent classification of the region as a biodiversity hotspot, I hope that this study helps further conservation efforts in the region.