A new species of the genus Neotropiella Handschin, 1942 (Collembola: Neanuridae) from Peru

Abstract Background Neotropiella is a genus of springtails which can be of medium size (2 mm) or relatively long (5 mm). These springtails live in leaf litter, under the bark of dead trees or in decomposing wood, mainly in the Neotropical Region and are often collected by litter samples on Berlese funnels or by pitfall traps. Most species have been described, based on relatively few specimens and chaetotaxy of several species is incomplete. New information A new species within Neotropiella was discovered in recent pitfall trap collections from Peru. Neotropiella peruana sp. n. was taxonomically treated and studied under both phase contrast and scanning electron microscopy. It is similar to N. insularis from Brazil, but smaller with only 4 mandibular teeth (vs. 5) and with well-developed unguis lateral teeth. Intraspecific variation of the new species is provided. We also present the first DNA barcodes for the genus.


Introduction
Members of the genus Neotropiella are often abundant in forest litter, but are also found in decomposing wood, bark and moss on branches of trees and even in epiphytic plants. They are often collected by Malaise traps, canopy fogging and by pitfall traps. The genus in mainly distributed in the Neotropical Region where 18 species have been listed (Abrantes et al. 2012, Queiroz et al. 2013. Most descriptions are very brief including the few specimens (one or two) as noted by Bellini et al. (2020) and, even in the four species for which the chaetotaxy was reported, no morphological variation was included.
The only species of this genus cited from Peru is Neotropiella carli (Denis, 1924) which can measure up to 5 mm long; the new species here described is less than half the size and has a stronger pigmentation and several different characters. It was collected by pitfall traps at San Ramón, Chanchamayo, fundo Génova. The locus typicus is Yunga lower montane forest (Fig. 1). a b Figure 1.

Materials and methods
Material from Peru was collected by the second author using pitfall traps and preserved in 96% ethanol. A total of 19 specimens were subsequently slide-mounted in Hoyers' solution at Laboratorio de Ecología y Sistemática de Microartrópodos, Faculty of Sciences, Universidad Nacional Autónoma de México for study.
For the Scanning Electron Microscopy (SEM) study, several specimens were dehydrated using a graduated series of ethanol dilutions, then dried using a critical point dryer (Baltec CPD030) and coated in gold using a Denton Vacuum Desk II ioniser.
For the molecular study, five specimens were photographed and sent for sequencing with the standard COI-5P marker ("DNA barcode", Ratnasingham and Hebert 2013) at the Canadian Centre for DNA Barcoding, University of Guelph.
For the morphological study, specimens or cuticles were mounted in Hoyer's solution after clearing the specimens. Some slides were remounted to study chaetotaxy and morphological variation.
Nineteen specimens (including vouchers and type material) were deposited in the following collections: LESM

Etymology:
The name is locative, after of the country where it was collected in Peru. The cuticles of four specimens were recovered and mounted in Hoyer's solution which represent the vouchers and are kept at the author's institution.  Genital plate of male.

Diagnosis
Neotropiella peruana sp. nov. is characterised by the combination of a ventral sensorial field on Ant IV with about 100 modified setae, small body size (1.2-2.2 mm) and small number of vesicles in the postantennal organ (26-28 in average). Mandibles have 4 teeth and maxillae with 2 lamella, 1 acuminate and 1 hooked. Th I with 4 pairs of smooth microsetae and Di area on Th II and III with 3 setae. 1 + 1 lateral tooth on unguis besides the inner 1 and often 1 + 1 subapical tooth.

Discussion
N. peruana sp. nov. shares with N. carli (Denis 1924) from Guyana and N. insularis Queiroz et al. (2013)   Anal vesicles. Queiroz et al. (2013) as having composed vesicles in PAO. Lawrence (1971) suggested the dubious value of vesicles for splitting species, based on a short series and he noted that specimens with a small number of vesicles have relatively larger size, showing a tendency to subdivide; the composed PAO that was supposed to be a differential character of N. insularis is variable and has no importance for the species delimitation.
Variation: For body length, only 14 specimens were measured (adults and juveniles) from the same locality. The average is 1.665 µm (range 1.250-2.250 µm). Ant IV sensilla have usually 6, but few specimens had 7-8 or even 5. Ant IV ventral file, from 65 to 116 modified setae (average 87). Eyes are mostly constant, 5 + 5, but in one case, there was one specimen with 5 + 4 eyes. PAO, minimum vesicles 20, maximum 53 vesicles, average 26-28. Mandibles always with 4 teeth. Maxilla always hooked. Labium always the same pattern, only one specimen had 0 + 1 postlabial seta. Unguis was studied in 17 specimens; they always had one inner tooth and 2 lateral teeth, but in 7 cases, there was one pair of subapical small teeth as shown in Figure 8. Head chaetotaxy seems to be constant. Body chaetotaxy variation was studied in 14 well preserved specimens, but only on Th. I and Abd. V was strong variation found. The seta m1 of Th I is always microseta (14 cases); m2 as microseta in 3 cases and as meso-or macroseta in 11 cases; m3 as microseta in 4 cases and meso-or macroseta in 8 cases; m4 is always microseta; lateral seta is always microseta. On Abd V, the seta p1 is always microseta; p3 is always the sensorial seta, p4 is always a microseta, seta p5 is microseta, in one case, it was macroseta, lateral seta p6 is always microseta. One specimen has one teratological antenna, where only the basal segment was present and at the tip one large sensillum, another has one teratology on leg II where the tibiotarsus was lacking. One female presents only 1 eugenital seta instead of 2 such setae.