The planthopper genus Spartidelphax, a new segregate of Nearctic Delphacodes (Hemiptera, Delphacidae)

Abstract The new genus Spartidelphax is described to house three species removed from the polyphyletic genus Delphacodes. The members of Spartidelphax are coastal species native to eastern North America, and probably feed exclusively on cordgrass (Poaceae, Spartina Schreb.). The taxonomy and nomenclature of the included species (viz. Spartidelphax detectus, Spartidelphax luteivittus, and Spartidelphax penedetectus) are reviewed. Spartidelphax luteivittus is a nomen dubium, whose type material is inadequate to provide diagnostic features contrasting with Spartidelphax detectus and Spartidelphax penedetectus. Diagnoses and a key are provided for the remaining Spartidelphax.


Introduction
Delphacodes Fieber, 1866, is a polyphyletic genus (e.g., Urban et al. 2010) with approximately 158 nominative species worldwide at this time (Bourgoin 2014. Delphacodes sensu stricto is composed of 10 species from the western Palearctic Diagnoses are provided for each species emphasizing putatively distinguishing features (full descriptions of detecta and penedetecta were provided by Beamer 1950). For the diagnoses, topotypic paratype males of D. penedetecta (Cedar Keys, FL) were dissected and illustrated and compared to available specimens of D. detecta. The male lectotype (designated by Oman 1947: 211) of D. detecta could not be located for this study, although the female paralectotype was found ( Figure 5; at ISUI) and included. Delphacodes luteivitta (Walker) is recorded only from the holotype in the British Museum (Natural History). For primary types, labels were quoted verbatim using "/" to indicate a line break and "//" to indicate a new label and with supplemental information given in brackets. For other material examined, label data are arranged into a consistent sequence, beginning with country, state or province, specific locality, collection date, and collector, with number, gender (as 'm' for males, 'f' females) and specimen depository given in parentheses. Specimens examined were provided 2D barcode labels and data were captured for online presentation (visualized at discoverlife.org and iDigBio.org) using "Arthropod Easy Data Capture" (Schuh et al. 2010, Schuh 2012, Arthropod Easy Capture 2013. Photographs and measurements of D. detecta and D. penedetecta were taken using a digital imagery system consisting of a Nikon SMZ1500 microscope, Nikon Digital Sight DS-U1 camera and NIS Elements Imaging software (version 3.0). Line art was digitally traced from photographs. All measurements are in millimeters (mm).
The holotype of Delphax luteivitta (as the BMNH) was examined and photographed (by MDW) to assess features of this specimen in comparison to Delphacodes detecta and D. penedetecta. Photographs were taken using a Leica M125 Stereomicroscope, Canon Digital EOS 550D camera with EOS Utility and Helicon Focus software.
Male terminalia with pygofer rather quadrate in lateral view, dorsocaudal margin of pygofer weakly projecting. Opening of pygofer broad, wider than long, with lateral margins of opening carinae, ventral margin smoothly rounded. Diaphragm strong and conspicuous, dorsal margin broadly U-shaped, bearing median, bilobed armature subtending the aedeagus, much wider than tall. Parameres exerted through broad opening in diaphragm; parameres strongly flattened, sides subparallel, strongly diverging, basal and apical angles weakly developed. Aedeagus widest in basal third, then abruptly narrowed with distal 2/3 strongly downcurved; suspensorium U-shaped, weakly apparent. Segment 10 broad, bearing strongly developed pair of weakly sinuate processes on caudal margins near lateral margins. Segment 11 about 2/3 height of segment 10.
Macropters darker than brachypters, with abdomen and lateral portion of mesonotum more strongly embrowned. Macropterous wings are clear (no dark marking at apex of clavus), exceeding length of abdomen nearly by length of abdomen.
Remarks. Spartidelphax penedetectus was chosen as the type species since the holotype of Delphax luteivitta is in unsatisfactory condition and the lectotype of Liburnia detecta could not be located (although putatively at the USNM). The holotype of Delphacodes penedetecta Beamer, 1950, is at SEMC.
Spartidelphax is phylogenetically placed at the base of a strongly supported clade with the genera Prokelisia Osborn, Neomegamelanus McDermott, and Tumidagena Mc-Dermott based on the phylogenetic investigation of Delphacidae using DNA nucleotide sequence data from four genetic loci (18S rDNA, 28S rDNA, wingless and cytochrome oxidase I) and 132 coded morphological characters by Urban et al. (2010). These three genera and Spartidelphax are associated with Spartina Schreb. (Poaceae, cordgrass), and are abundant in salt marshes in eastern North America. Prokelisia, Neomegamelanus, and Tumidagena are more slender forms with their body weakly to strongly compressed, and their vertex more strongly projecting. Members of Prokelisia are most similar, including having the carinae on their frons bordered by dark (except P. crocea), but they are more slender, usually with the frons broadest ventrally, parameres either distally converging or slender and diverging, and the aedeagus is usually upturned. Superficially more similar to Spartidelphax are species now placed in Muirodelphax Wagner, but North American species in this genus lack processes on segment 10. Also similar are Toya Distant, Metadelphax Wagner, and Syndelphax Fennah, but the dorsocaudal angles of the male pygofer of these genera are greatly expanded (Gonzon and Bartlett 2008).
In the "Key to genera of Delphacidae North of Mexico" of , Spartidelphax keys to couplet 75, where Spartidelphax can be inserted in place of the entry for Delphacodes detecta and D. penedetecta.
Etymology. The generic name is an arbitrary combination of letters formed by combining a truncation of Spartina (the host grass genus) with -delphax, a common termination used in delphacids. The name is to be treated as masculine (Delphax was affirmed as masculine by ICZN 1961). Diagnosis. Slightly larger than S. detectus, with vertex longer than wide (l:w 1.34-1.48), aedeagus with a pair of rows of fine ventral serrulations in distal third; base less abruptly narrowed than in S. detectus. Parameres in widest view subtly more narrowed on outer angle than S. detectus, outer angle slightly curled.
Type locality. New York City, NY. Diagnosis. Slightly smaller than S. penedetectus, with wider vertex (l:w ratio averaging between 1.25-1.31). Aedeagus with 2-3 rows of lateral teeth in distal third on both sides of aedeagus; base of aedeagus abruptly narrowed at about 2/3 length; distal portion of base with fine flange on right side. Parameres in widest view more rounded on outer angle than S. penedetectus.
Length ♂2.5 mm, ♀3 mm" (for brachypters). Beamer (1950) redescribed S. detectus did not report body lengths except by quoting Van Duzee (1897: 248), who specified male 3½ mm, female 4 mm for the macropterous syntypes (yielding a length comparison between brachypterous penedetectus and macropterous detectus). Here we clarify that penedetectus is the larger species (detectus brachypterous males 2.28 mm, macropterous males 3.29 mm, vs. penedetectus brachypterous males 2.33 mm, macropterous males 3.78), although body length does broadly overlap between species. The vertex l:w ratio is approximately 1.25-1.31 for detectus and 1.34-1.48 for penedetectus. For penedetectus Beamer (1950) also noted that crown is narrowed toward the apex. This  The most definitive feature that distinguishes the two species is the aedeagus (Fig.  4B, D). In S. detectus the aedeagus has rows of small teeth on both sides of the apical third, tracing the curve of the aedeagus, with one row extending nearly to the expanded basal portion of the aedeagus. In S. penedetectus, the aedeagus bears a pair of rows of ventral aedeagal teeth, reduced to fine serrulations in the type series. Raupp and Denno (1979) found that the density of Spartidelphax detectus on Spartina patens exceeded 400 per kg of live grass sampled over a 6-month period, and was described as a dominant herbivore on S. patens by Denno (1977). It appears to have 3 non-synchronous generations per year in New Jersey, and overwinters as 4 th or 5 th instar (Denno 1976(Denno , 1977. Populations are wing polymorphic (both brachypters and macropters present within a population), with proportions of wing brachyptery and macroptery varying based on complex interactions of seasonal, environmental and population variables. An overall annual brachyptery rate of 86% (out of 23,868 specimens) was reported by Denno (1980) in New Jersey. Denno (1980)    Remarks. The male holotype of Delphax luteivitta (at BMNH) is in poor condition (Figs 6-7). The specimen is shriveled and damaged, making the proportions of the head suspect. The coloration and habitus are similar to the other species of Spartidelphax. The wings are frayed and fragmentary with the forewing of only one side complete (mounted on specimen card, Fig. 7A). The abdomen has been removed for dissection, and only portions of the abdomen remain. The aedeagus (Fig. 7) although similar to the other species of Spartidelphax is missing the distal third, which bears the most definitive features separating S. detectus and S. penedetectus, with much of the base obscured by an adhered membrane.

Discussion
Spartidelphax detectus and S. penedetectus are closely allied species. The lack of published records of S. penedetectus on the Atlantic coast may be because of the great similarity of these species, the numerical over-dominance of S. detectus in coastal marshes, and that most records of S. penedetectus were from the Gulf coast, so planthopper workers may not have expected, or sought, S. penedetectus on the Atlantic coast. Targeted collections on Spartina alternifolia should find Spartidelphax penedetectus throughout the Atlantic coast.
Our original intention was to determine whether S. luteivittus was a senior synonym or a valid species. The very poor condition of the holotype obscured all of the most useful features distinguishing S. detectus from S. penedetectus, and also did not obviate the possibility that S. luteivittus represents a third valid Spartidelphax taxon. We also studied morphological variation within the species over the geographic distribution of Spartidelphax, and found variation in size, shape details of the parameres, armature of the diaphragm, and shape and serration of the aedeagus; but were able to attribute males of all the examined specimens to either S. detectus or S. penedetectus. However, a field investigation to collect Spartidelphax from the different species of Spartina (including species not yet implicated as hosts such as Spartina bakeri Merr., S. cynosuroides (L.) Roth, S. pectinata Bosc ex Link, and S. spartinae (Trin.) Merr. ex Hitchc.) is needed to determine if there are additional species of Spartidelphax. In the meantime S. luteivittus is best treated as a nomen dubium.