A new species of Ceraeochrysa Adams (Neuroptera, Chrysopidae), with a key to the species from Mexico

Abstract The genus Ceraeochrysa Adams is widely distributed in the New World, from southeastern Canada to Argentina, with 15 out of 61 previously known species recorded in Mexico. In this paper, Ceraeochrysa tacanensissp. nov. is described and illustrated from Volcán Tacaná, Chiapas, and an identification key to Ceraeochrysa species present in Mexico is provided. The new species is similar to others with swollen and darkened posterior branches of the cubital vein, and it can be separated from these other species by an elongate gonapsis extending from the base of the gonosaccus; the gonapsis is slightly upturned, terminating in a rounded apex with dorsal microteeth. Females of the new species have non-distinctive genitalia morphology. However, they can be associated with males of the species by body color pattern, synchrony, and sympatry.


Introduction
The Neotropical green lacewing genus Ceraeochrysa (Neuroptera, Chrysopidae) was separated from Chrysopa by Adams (1982), who based his definition of the genus on male genitalic characters and recognized 24 species. Further studies added several species to this genus (Brooks and Barnard 1990;Penny 1997Penny , 1998Penny , 2002Tauber et al. 2000;Freitas and Penny 2001;Tauber and De León 2001). Ceraeochrysa is the second most species-rich chrysopid genus in the New World after Leucochrysa McLachlan, comprising 61 valid species Freitas 2010, 2011;Tauber and Flint 2010;Tauber and Garland 2014).
This genus is distributed from southeastern Canada to Argentina, and its greatest species richness and abundance is in the tropics (Adams 1982;Brooks and Barnard 1990;Freitas et al. 2009;Tauber et al. 2000;Sosa and Freitas 2010). Currently, countries having the highest species richness of Ceraeochrysa include Brazil (33 species), Costa Rica (23), Mexico (15), Panama (14), and Venezuela (12) (Freitas et al. 2009;Sosa and Freitas 2010;Oswald 2018;Martins and Machado 2019). Species of this genus have been reported from dry and open forests and various agroecosystems (Tauber et al. 2000;Freitas et al. 2009). Their larvae are trash-bearers and feed on soft-bodied arthropods such as aphids, diaspidids, thrips, aleyrodids, psyllids, and neonatal larvae of Lepidoptera, which makes them potentially useful for biological control (Tauber et al. 2000;Freitas 2001;Penny 2002;Freitas et al. 2009).
There have been few studies of the Chrysopidae of Mexico, and knowledge of this group is fragmented. The aim of this paper is to describe and illustrate a new species of the genus Ceraeochrysa as part of a survey of the lacewings of the Tacaná Volcano, Chiapas across an altitudinal gradient. Also, a key to males of the species of this genus known from Mexico is included, excluding C. indicata (Navás) and C. lateralis (Guérin-Méneville) for which males are unknown. Due to their potential importance in the biological control of agricultural pests, there is an established need to better describe the green lacewing fauna of Mexico.

Materials and methods
The material examined was obtained during monthly samplings (February 2018-January 2019) in the Tacaná Volcano Biosphere Reserve, Chiapas state, Mexico. Specimens were captured at lights traps and with aerial net on vegetation, kept alive in plastic screw cap vials, then they were pinned as they died, or after being killed by freezing. For dissection of genitalia, the abdomen was cut between the 6 th and 7 th segments and the apical segments were removed and cleared with solution of 10% potassium hydroxide (KOH) for 15 min at 80 °C in a water bath. The cleared genitalia were stained using Clorazol Black E and then placed in microvials with glycerin. Observations were done under a Discovery V8 Zeiss dissecting microscope. Serial images from different layers were taken with a Zeiss Axio Zoom V16 microscope fitted with an AxioCam MRc5 digital camera and stacked using Zen 2012 (Blue edition). Head width was measured as the distance between the outer margins of the eyes, dorsally. Wing length was measured from the joint region to the apex (Sosa and Freitas 2010). The holotype and allotype, both dissected, are deposited at the Colección Nacional de Insectos (CNIN) of the Instituto de Biología, UNAM, Mexico City; paratypes will be deposited at CNIN, the Colección de Insectos asociados a plantas cultivadas en la Frontera Sur (ECO-TAP-E) and the National Museum of Natural History, Smithsonian Institution (NMNH), Washington, DC. The key was constructed based on Freitas et al. (2009). Diagnosis. This species has marks on the pronotum (a discontinuous red lateral stripe) and on the meso-and metanota (two anterior reddish black spots on each) (Fig. 1B) and on the abdominal tergites (orange to dark-brown lateral elongate marks) (Fig. 1D); forewing has the posterior branches of the cubital vein swollen, darkened and edged with dark on the membrane; last tarsal segments are darkened (Fig. 1A). The gonosaccus basally bears gonosetae (Fig. 3A); the arcessus is very long, narrow, straight, with curved apical point (Fig. 3B); the gonapsis is elongate, its basal section extends internally from the base of gonosaccus and is slightly upturned, terminating anteriorly in a smoothly rounded apex (Fig. 3E), the distal section extends externally and terminates dorsally with microteeth (Fig. 3D); a membranous sac between apices of gonapsis and sternite 9 bears a field of well-developed gonocristae (Fig. 3A).
Variation. Lateral stripes of pronotum are variable, for instance whether they are continuous or interrupted ( Fig. 2A, B), thickened or narrow (Fig. 2C, D), pale or dark red (Fig. 2E, F); also, dorsolateral marks of the abdomen are generally orange, but may be reddish brown.
Etymology. This species is named after the Tacaná Volcano, located in the state of Chiapas, Mexico, where the specimens were collected.
Ecology. This species is presently known from cloud forest (1,430-1,705 m a.s.l.) and mixed oak-cloud forest (2,060-2,430 m a.s.l), and with similar collecting techniques and collecting effort, it was not found at lower (661-1,393 m a.s.l.) or higher (2,884-3,246 m a.s.l) elevation collecting sites. Specimens were found on Alinus sp., Quercus sp., and Saurauia sp., and were collected from February through May, August through December 2018, and January 2019.

Discussion
Ceraeochrysa tacanensis sp. nov. shares the posterior branches of the cubital vein swollen and dark, V-shaped marking with C. angulata (Navás), C. angusta Freitas & Penny, C. digitata Freitas & Penny, C. elegans Penny, C. nigripedis Penny, and C. tauberae Penny. Also, an elongate arcessus is shared with these species (except C. angulata and C. digitata), plus C. bitacornua Freitas & Penny. The new species differs from the former species because it has a discontinuos stripe on the pronotum, while the rest have spots (C. angulata, C. angusta, C. elegans, C. nigripedis, and C. tauberae) or a continuous stripe (C. bitacornua and C. digitata). Another species with a discontinous stripe on the pronotum is C. pittieri Sosa & Freitas (Sosa and Freitas 2010: figs 4, 5), however, this species does not share other traits as explained above. In addition, C. tacanensis sp. nov. shares marks on the abdominal tergites with C. elegans, although the tarsal segments are darkened apically in the new species, as in C. nigripedis. Regarding genitalia, the new species is most similar to C. nigripedis, sharing a simple dorsal apodeme, an elongate gonapsis, and the shape of the gonarcal complex. However, the new species has a gonosaccus with gonosetae and a membranous sac with gonocristae between apex of gonapsis and sternite 9, similar to C. elegans. The sclerotized microteeth extended on the dorsal side of the gonapsis apex may be a unique trait of the new species (also present in the unrelated C. sanchezi), while C. elegans has microteeth restricted to the apex.