Kymachrysa, a new genus of Nearctic Green Lacewings (Neuroptera, Chrysopidae, Chrysopini)

Abstract Two North American species of green lacewings have undergone a number of changes in their generic assignments and are currently classified as incertae sedis. Here we demonstrate that adults (both sexes) and larvae of these species share a set of features that distinguishes them from currently described genera. Thus, to promote nomenclatural stability in Chrysopidae, we describe Kymachrysa, a gen. n. that contains the two species – Kymachrysa intacta (Navás), comb. n. and Kymachrysa placita (Banks), comb. n.. Also, we present modifications for the current generic-level key, illustrations, as well as biological information for identifying the genus and its known species.


Introduction
The green lacewing tribe Chrysopini (Neuroptera: Chrysopidae) includes seventeen genera in the New World; ten of these occur in the Nearctic. These New World genera are distinguished from each other on the basis of both adult (male and female), as well as larval, characters (e.g., see Brooks and Barnard 1990;Tauber 1974Tauber , 1975Tauber , 2003Adams and Garland 1982;Brooks 1994;Penny et al. 2000;Tauber and de Leon 2001;Tauber et al. 2000Tauber et al. , 2014Freitas and Penny 2001). However, the adult and larval characteristics of two Nearctic species were shown to be inconsistent with the genera to which the species had been assigned (Ceraeochrysa and Chrysopodes), nor could they be assigned to any other known chrysopine genus (Tauber and Flint 2010: 64). Most recently, they were retained temporarily in Ceraeochrysa (with the caveat of incertae sedis) (Tauber and Flint 2010: 64). Here, to foster nomenclatural stability, we describe a new genus to accommodate these two species (original names: Chrysopa placita Banks and Chrysopa intacta Navás), and we provide information for their identification.

Specimens and methods
Our procedures were those used in previous publications (e.g., Tauber et al 2012, Silva et al. 2013. We examined specimens from the following collections: Type-species. Chrysopa placita Banks, 1908: 259. Distinguishing adult features. Kymachrysa adults appear to be typical chrysopine lacewings of medium size and green coloration. Their most distinctive adult features occur in the male and female terminalia; in addition, a few external features are diagnostic of the genus: External features. (i) The longitudinal (radial) veins between the first and second rows of gradate veins of the fore and hind wings are sinuous (Fig. 1A, B), whereas in most other chrysopid genera they are relatively straight. (ii) In both males and females, the fused ninth tergite and ectoproct is completely divided by a dorsal invagination, and each side of the terminal abdominal segment is rounded posterolaterally (especially in males) ( Fig. 1C-F). Among other New World genera, a complete dorsal invagination of the T9+ect is reported only for Chrysopiella and Parachrysopiella (Brooks and Barnard 1990 Male terminalia. One of the most striking aspects of the Kymachrysa male terminalia is the S8+9, which is entirely fused and well sclerotized as in most chrysopine genera. However, in lateral view, the Kymachrysa S8+9 has an unusual ventral bend, and the ventral apodeme is heavy and elongate -extending anteriorly well beyond the proximal margin of S8 ( Fig. 2A, B). In ventral view, S8+9 is constricted mesally and rounded both anteriorly and posteriorly (Fig. 2C, D). These features are unique among New World chrysopids. Gonocornua are present on the gonarcal bridge, as in Ceraeochrysa. In Ceraeochrysa, the gonocornua are usually rounded and unarticulated, and they arise laterally from the gonarcal bridge (see Freitas et al. 2009). But, the gonocornua of Kymachrysa are unusual in that they appear at least partially articulated or separated from the gonarcal bridge, and at the base they are juxtaposed and located mesally on the distal margin of the gonarcal bridge (Fig. 2E, F). Furthermore, the dorsum of the mediuncus has a distinct, trough-like shape not found in other genera; the terminus has a weak, lightly sclerotized or membranous beak mesally and expanded membranous sacs laterally.
Female terminalia. Two notable features distinguish the female genitalia. (i) This chrysopid genus is the only one outside of the tribe Belonopterygini (see Tjeder 1966: 235, 324, 337) in which the female is reported to have a praegenitale. [Note: the recording of a praegenitale for Leucochrysa (data matrix of Brooks and Barnard 1990: Table 1) appears to be an error -the description of the genus, p. 248, states that the structure is absent.] Moreover, the structure appears unique among chrysopids, in that it is asymmetrical (a condition not reported for Belonopterygini) (Fig. 3C, D). (ii) The spermatheca is shaped like a pillbox with a shallow invagination and a sail-shaped velum that opens via a slit to the bursal duct ( Fig. 3F-H). By comparison, in Ceraeochrysa the spermatheca is cylindrical, with an elongate invagination and a U-shaped or J-shaped bend that opens via a slit directly to the bursa copulatrix (e.g., Adams and Penny 1985, Freitas and Penny 2001, Sosa and Freitas 2010. And, in Chrysopodes the spermatheca is cylindrical or tubular, with a very deep invagination and an elongate bursal duct (e.g., Adams and Penny 1985, Freitas and Penny 2001, Tauber 2010, Tauber et al. 2012). (iii) Finally, the Kymachrysa spermathecal duct (mature specimens) is hairy for almost its entire length; the terminal bristles are long and fine, and their length decreases proximally; at the base of the duct the bristles are very short and stubby, or granular in appearance (Fig. 3E, F).
Etymology. The prefix "Kyma-" comes from the Greek word kýma (κύμα), meaning wave, and refers to the wavy, or sinuate, longitudinal veins between the gradate veins of the forewings that distinguish the two species currently assigned to the genus. The suffix follows the traditional series of chrysopid names ending in "-chrysa" -Greek, feminine, "χρυσα" meaning golden.
Geographic distribution. The genus, which currently includes only two species, appears to be restricted to North America (Canada, United States and Mexico, as far south as Mexico City) (Adams 1982, Tauber 2003, Valencia Luna et al. 2006, Garland and Kevan 2007, Freitas et al. 2009, Tauber and Flint 2010. Characteristics of Kymachrysa larvae. The larvae of only one of the Kymachrysa species (K. intacta) were described (Tauber et al. 1998, as Ceraeochrysa placita). Later they were shown to share a large number of distinctive characteristics with the larvae of several species of Chrysopodes, and as a result the species was transferred to Chrysopodes (Tauber 2003, as C. placita).  Adams & Penny]. Comparisons with these species confirm that K. intacta larvae differ only slightly from those of Chrysopodes. And, given the large percentage of species in both Kymachrysa and Chrysopodes with undescribed larvae, it is not clear at this time, which, if any, of these differences will be informative at the generic level.
Nevertheless, the following features appear most noteworthy: (a) Setae: Previously, certain setae on the K. intacta Semaphorant B were reported to be "serrated" or "thorny", similar to those on Chrysopodes; these setae include the LS of the thorax and A4-A8, the large LDS on A6 and A7, and some dorsal thoracic setae ("serrated": Tauber  (b) Metathoracic fold: One of the primary reasons for transferring K. intacta to Chrysopodes (Tauber 2003, as C. placita) was the shared characteristic of an unusual posterior fold on the larval metathorax. In both taxa, the fold rises well above the anterior part of the metathorax, and it bears a transverse row (R1) of robust setae that stem from enlarged chalazae and that are usually slightly longer than the submedian setae (SMS) on abdominal segments A1 through A6. However, subsequent comparisons indicated that aspects of this feature present some small, but significant differences between K. intacta and Chrysopodes.
First, as discussed above, the surface of the R1 setae on K. intacta Semaphorant B is distinctive. It is sabulose (sandy), not thorny as in Chrysopodes.
Second, although the body dimensions of the L3 larvae of Chrysopodes (Chrysopodes) and K. intacta that we studied are similar, the length, robustness, and stiffness of the setae differ between the two taxa (Table 1, Fig. 9). For example, in Chrysopodes (Chrysopodes), the R1 setae range in length between 0.28-0.42 mm, and they are thick and erect throughout their entire lengths. In comparison, the K. intacta R1 setae range between 0.48-0.62 mm; they are slender throughout, and only the basal section stands erect -the distal section tends to curve. [Note: In the large bodied Chrysopodes (Neosuarius) collaris (Schneider), both the R1 setae and SMS are slightly longer and more slender and flexible than those of Chrysopodes (Chrysopodes) species (Table 1).] Third, the larvae of Chrysopodes spp. (all instars, including the first) have dark brown markings on the frontal surface of the chalazae in metathoracic R1; these markings are elliptical to ovate and at least as broad as the setal base. In K. intacta (second and third instars) they are light brown in color, elongate, and narrower than the setal base (Fig. 9A, B); they are either absent or very light in first instars.
Biological features of Kymachrysa. Adult specimens of K. placita are not common; those that we have seen were collected during July and August. No larval specimens are reported. K. intacta appears to be more abundant; we have seen adult specimens collected from June through mid-October (mostly August), and we have collected larvae during March and April (overwintering second instars) and in September and October (prehibernal first instars).
Biological features have been investigated only for K. intacta (Tauber et al. 1998). In populations from both eastern and western USA (NY and CA), eggs are laid and larvae occur on the trunks of medium-sized to large-sized deciduous and evergreen  trees. The larvae are debris-carriers; typically they carry pieces of bark or other woody or plant material that blends with their typical substrate (Fig. 10). Developmental stages are relatively prolonged, and they are strongly influenced by photoperiod (Tauber et al. 1998). The life cycle appears to be univoltine. Larvae overwinter as diapausing second instars. Short daylengths decelerate development during the first instar, and they induce and maintain hibernal diapause in second instars. Daylength also may be important during the postdiapause developmental period. Under field conditions (Tompkins and Schyler Counties, NY), adults emerge in June, and eggs occur from July through late September or early October. Such a life cycle is unusual, but not unknown, for other chrysopids. For example, free-living second and third instars of Pseudomallada species also overwinter in a photoperiodically induced diapause (Principi and Sgobba 1987, 1993, Canard et al. 1990).
Kymachrysa's generic relationships. With the addition of Kymachrysa, a total of 17 genera of Chrysopini are now known from the New World. Table 2 lists the eleven that are reported from North America, including Mexico, and it provides references to their distributions.
Above, we showed that Kymachrysa adults (males and females) express a number of characteristics that provide strong morphological support for a distinct genus. However, its relationship with other chrysopine genera remains perplexing. In general, the male genital structures resemble those of Ceraeochrysa, whereas the female genitalia (apart from the presence of a praegenitale in Kymachrysa) appear similar to those of several other genera (e.g., Ungla, Pseudomallada). Finally, its larval morphology is very close to that of Chrysopodes, and its biological traits (larval habitat, overwintering stage, photoperiodically controlled diapause) resemble those of Pseudomallada. Resolution of the dilemma posed by the above mixture of similarities awaits a broadly based phylogenetic analysis of chysopid genera.

Modifications for Brooks and Barnard's (1990) key to adults of chrysopid genera
In the most recent taxonomic key for chrysopid genera (Brooks and Barnard 1990), both Kymachrysa and Ceraeochrysa males are recovered at couplet 45. However, the two species can be differentiated with the following changes and additions to the couplet:
Specimens of K. intacta from eastern and western North America appear very similar to each other, but we found some geographic variation of note. First, the male abdominal sternites are densely covered with microtholi on our specimens from California (Alameda, Kern, and Sierra Counties) (Fig. 8B). In contrast, microtholi are very sparse or absent on specimens from Utah (Wasatch County) and Colorado (Larimer County), and absent from specimens from New Hampshire (Belknap County) and New York (Tompkins and Schuyler Counties) (as in Fig. 8 for K. placita; also see Garland 1982). Second, larvae (second and third instars) from the west were reported to have somewhat denser abdominal setation than those of the east (Tauber et al. 1998). And, finally, the length of the stalk that supports the egg is considerably longer in east-ern than in western populations (eastern: 2.1-3.3 mm; western: 1.4-2.3 mm) (Tauber et al. 1998). Given the potential role of microtholi in courtship, we suspect that the above variation may indicate at least some reproductive isolation between eastern and western populations.