Spinanycta alabamensis Espinasa, Gutierrez & Niemiller, 2024

Espinasa, Luis, Gutierrez, Abrianna, Hinkle, Amata & Niemiller, Matthew L., 2024, A new genus and species of nicoletiid silverfish (Insecta, Zygentoma, Nicoletiidae) from caves of northern Alabama, USA, Subterranean Biology 49, pp. 1-17 : 1-17

publication ID	https://doi.org/ 10.3897/subtbiol.49.119986
publication LSID	lsid:zoobank.org:pub:9E75D5C3-7463-4D6F-BA74-FAD836472904
DOI	https://doi.org/10.5281/zenodo.11262135
persistent identifier	https://treatment.plazi.org/id/C206E814-6029-596B-8BB7-59AE13999653
treatment provided by	Subterranean Biology by Pensoft
scientific name	Spinanycta alabamensis Espinasa, Gutierrez & Niemiller
status	sp. nov.

Treatment

Spinanycta alabamensis Espinasa, Gutierrez & Niemiller sp. nov.

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Type material.

Holotype: male 8.5 mm, from Bobcat Cave (34.6686 ° N, 86.7130 ° W), Alabama Cave Survey (ACS) no. AMD 1283 . Redstone Arsenal, Madison County, Alabama, USA, deposited into the Entomology Collection at the Auburn Museum of Natural History ( AUM 221500 View Materials ), collected 26 November 2019 by Matthew L. Niemiller, Joseph Lamb, Amata Hinkle, and Brian Stoltz (field code MLN 19-050). GoogleMaps

Paratypes: 3 ♀ paratypes with same collection information as holotype ( AUM 221501 – 221503 ) GoogleMaps ; 1 ♂, 3 ♀ paratypes from Bobcat Cave collected on 6 October 2020 by Matthew L. Niemiller, Joseph Lamb, and Amata Hinkle (field code MLN 20-036.6) ( AUM 221504 – 221507 ) ; and 1 ♂, 1 ♀ from Bobcat Cave collected 13 September 2023 by Amata Hinkle, Brendan T. Cramphorn, Jared P. Higgs, and Eric C. Maxwell (field code BTC 23-019 - 1) ( AUM 221508 – 221509 ) .

Additional material: 2 ♂, 2 ♀ from Muddy Cave (ACS no. AMD 1095 ), Madison County, Alabama, USA, collected 15 June 2020 by Matthew L. Niemiller, K. Denise Kendall Niemiller, Amata Hinkle, Joseph Lamb, and Katherine E. Dooley (field code MLN 2020-021.1) ( AUM 221510 – 221513 ) ; 1 ♂, 2 ♀ from Muddy Cave collected 7 July 2022 by Matthew L. Niemiller, Brendan T. Cramphorn, and Eric Cline (field code BTC 22-110 - 3) ( AUM 221514 – 221516 ) .

1 ♀ from Rockhouse Cave (ACS no. ALM 312), Wheeler National Wildlife Refuge, Limestone County, Alabama, USA collected 21 May 2020 by Matthew L. Niemiller, K. Denise Kendall Niemiller, Amata Hinkle, and Katherine E. Dooley (field code MLN 20-020.6) ( AUM 221517 ) .

Etymology.

S. alabamensis . Derived from the word Alabama, the state where the species was discovered.

Type locality.

USA. Alabama, Madison County, Bobcat Cave (ACS no. AMD 1283) on Redstone Arsenal. Redstone Arsenal is a 154.8 km 2 United States Army installation in southwestern Madison County adjacent to the city of Huntsville. Redstone Arsenal is host to more than 75 tenant agencies, including the Department of Defense, Department of Justice, Federal Bureau of Investigation, and, most notably, the National Aeronautics and Space Administration’s Marshall Space Flight Center. Bobcat Cave is located near the western border of Redstone Arsenal (34.6686 ° N, 86.7130 ° W) on a small knoll. Redstone Arsenal and Bobcat Cave are situated within the Tennessee River District of the Highland Rim section of the Interior Low Plateau Province. The cave is developed in the Tuscumbia Limestone with a mapped length of 454.1 m (1,490 ft) and vertical extent of 6.4 m (21 ft). Much of the cave consists of a series of low and broad passages connected by tight crawlways with little exposure of bedrock. Water levels in the cave respond quickly to heavy precipitation and can flood completely. Significant flooding events continually deposit mud on nearly all surfaces in the cave. It is on these mud substrates and under the few mud-encased rocks nearer the entrance that most Spinanycta alabamensis have been found. In addition, individuals have been observed on the surface of isolated pools in the Shrimp Room, the largest room in the cave (61 m by 30.5 m).

Description.

Male holotype 8.5 mm (Fig. 2 A View Figure 2 ) from Bobcat Cave, collected 26 November 2019. Thorax width 1.5 mm. When complete, antennae about 1.25 × the length of the body and tails about 0.75 ×. General color whitish, yellow (Fig. 2 A View Figure 2 ). When complete, antennae are about 1.25 × the length of the body and tails about 0.75 × the length of the body. Pedicellus about half the length of the scape, with unicellular glands clustered ventrally in four groups with a row of microchaetae bordering them in form of a “ U ”. On its lateral outside side there are an extra two groups of unicellular glands in a large, bulbous projection (Fig. 2 B, C View Figure 2 ). Female pedicellus simple and slightly less than half the length of the scape. Head with about 6 + 6 macrochaetae near the insertion of each antenna (Fig. 2 D, E View Figure 2 ).

Mouthparts as shown in Figs 2 F – L View Figure 2 , 3 A View Figure 3 . Appendages longer than epigeomorphic species, but shorter than highly troglomorphic nicoletiids. Labial palp’s apical article’s long. Its width is about 2 / 3 its length and slightly longer than the penultimate article (Fig. 2 F – G View Figure 2 ). As in other cave-adapted nicoletiids with long appendages, the bulge containing 2 macrochaetae in the penultimate article of the labial palp is not too prominent (Fig. 2 F View Figure 2 ). Labium and first article of labial palp with macrochaetae. The sensilla of the labial palp are longer than other American nicoletiids due to being supported by a longer than common trunk (Fig. 2 H View Figure 2 ). Last article of maxillary palp 1 / 3 longer than the penultimate article (Fig. 2 I View Figure 2 ). Apex of lacinia as in Fig. 2 J View Figure 2 . Apex of galea with two conules; one longer than wide and the other wider than long (Fig. 2 K View Figure 2 ). Apex of maxillary palp as in Fig. 2 L View Figure 2 . Mandible chaetotaxy with 4 macrochaetae (Fig. 3 A View Figure 3 ).

Thorax as in Fig. 3 B, C View Figure 3 , with 1 + 1 macrochaetae on their lateral sides plus several posterolateral. Legs not too long when compared to other troglobitic nicoletiids, as shown in Fig. 3 D View Figure 3 . Hind tibia approximately 5 times longer than wide and approximately 3 / 4 length of tarsus. Claws of the praetarsus and empodium with a hairy appearance covered basally with small microtrichiae, similar to Molero-Baltanás et al. (2020; fig. 23). Abdominal sterna II – VII subdivided into coxites and sternites (Fig. 3 E View Figure 3 ). Sterna I, VIII and IX of male entire. Styli on sterna II – IX. Sterna I of males modified with a long, narrow point extending to the apex of sterna II (Fig. 3 E – G View Figure 3 ). This point has in its center a groove surrounded by many macrochaetae that extends to the base of sterna I (Fig. 3 F View Figure 3 ). No apparent modifications in male’s sterna III and IV.

Posterior end of urotergite X with a 1 + 1 long macrochaetae (Fig. 3 H, I View Figure 3 ), similar to Nicoletia phytophila Gervais, 1844 ( Espinasa et al. 2011; Fig. 1 C, D View Figure 1 ). Distance between macrochaetae about the same as the length of the macrochaetae. Area between the distinct macrochaetae with a small concavity (Fig. 3 I View Figure 3 ). Cercus of adult male with a longer than wide basal annulus with one small spine, followed by a longer annulus, with multiple subequal spines (Fig. 3 I, J View Figure 3 ). Female cerci without modifications.

Urosternum VIII of adult male flat between the insertion of the styli (Fig. 4 A View Figure 4 ), without an emargination bordered by projections, as in other Cubacubaninae . Point of insertion of parameres in urosternum IX deep and with coxal processes with several setae slightly more sclerotized (Fig. 4 A, B View Figure 4 ). Parameres as in Fig. 4 A, B View Figure 4 . Parameres barely surpass the base of styli. Paramera with a distal semi-eversible vesicle and with some short, modified setae (Fig. 4 B View Figure 4 ). Stylus IX with 2 macrochaetae and an extra subapical pair, and larger than other styli (Fig. 4 A View Figure 4 ). Other styli with 1 macrochaetae plus subapical pair. Terminal spine with one small tooth.

In adult females, the ovipositor surpasses apex of stylus IX between 3 and 3 + 2 / 3 the length of the stylus IX (Fig. 4 G View Figure 4 ). Gonapophyses with about 21–22 divisions. The subgenital plate has a subtriangular shape (Fig. 4 E, F View Figure 4 ) that ends in a slight point (Fig. 4 G View Figure 4 ), similar to the one in Nicoletia phytophila ( Espinasa et al. 2011; Fig. 1 A, E View Figure 1 ), although the slight point is less prominent in the new species.

Postembryonic development.

Males at 5.5 mm have no glands in pedicellus, no spine in urosternum I, or spines in cerci, but they already have paramers. At 6.5 mm they have glands in the pedicellus, the spine in urosternum I reaches about ¾ of the apex of urosternum II, and spines in cerci are small. At 7 mm the spine reaches the apex of urosternum II and by 8.5 mm it surpasses by 1 / 10 the length urosternum II.

Females at 5.5 mm have an ovipositor that barely surpasses the apex of stylus IX and gonapophyses with about 15 divisions. By 7 mm ovipositor surpasses apex of stylus IX by about 2 + 2 / 3 the length of the stylus and the gonapophyses has the adult number of 21–22 divisions. Between 7.2 mm and 10.5 mm in the largest available specimen the ovipositor surpasses stylus IX by between 3 and 3 + 2 / 3 the length of the stylus.

Geographic distribution.

The species is known to date only from three caves, all developed in the Tuscumbia Limestone and located along the northside of the Tennessee River in southern Madison and southeastern Limestone counties. The largest population at Bobcat Cave is located on Redstone Arsenal. Muddy Cave is owned and managed by the Land Trust of North Alabama and is located 15.1 km SE of Bobcat Cave adjacent to a large residential area. Rockhouse Cave is located 16.5 km SW of Bobcat Cave and is developed in an exposure of limestone, Rock House Bluffs, on the north shore of the Tennessee River on Wheeler National Wildlife Refuge. The current distribution represents an EOO of 124.1 km 2 and AOO of 12.0 km 2.

Habitat and ecology.

At Bobcat Cave, Spinanycta alabamensis has been observed actively crawling on mudbanks and underneath mud-covered cobble and rocks adjacent to pools in the dark zone below the slope from the entrance and throughout the Shrimp Room (Figs 5 View Figure 5 , 6 View Figure 6 ). On two occasions, individuals were observed on the surface of a pool. As many as 20 individuals have been observed during a survey at Bobcat Cave (Table 1 View Table 1 ). At Muddy Cave, individuals have been observed on mudbanks and underneath mud-covered cobble near pools primarily before the tight crawl to the northern section of the 348 - m (1143 - ft) cave system. A single individual has been observed and collected at Rockhouse Cave. A female was found under a small (12 - cm diameter), loose, but mud-covered rock adjacent to an isolated pool in a fissure in the northern section of the 384 - m (1259 - ft) long cave system. All observations to date have been made in sections of the three cave systems that completely flood during heavy precipitation events. Spinanycta alabamensis co-occurs with several other troglobiotic taxa, including the spiders Phanetta subterranea (Emerton, 1875) and Liocranoides unicolor Keyserling, 1881 , millipede Scoterpes sp. Cope, 1872, springtail Pseudosinella sp. Schaeffer, 1897, two-pronged bristletail Litocampa sp. Silvestri, 1933, and isopod Miktoniscus sp. Kesselyak, 1930.

Conservation.

Spinanycta alabamensis is known currently from three caves in southern Madison and southeastern Limestone counties, Alabama. The species was assessed as Imperiled (G 2) under NatureServe criteria and as Endangered B 1 a under IUCN Red List criteria because of few known occurrences, a small and potentially restricted geographic range, high intrinsic vulnerability, and several current and potential threats to populations. All three caves occur on protected lands: Bobcat Cave on Redstone Arsenal, Rockhouse Cave on Wheeler National Wildlife Refuge, and Muddy Cave is owned by the Land Trust of North Alabama. Populations face several existing and potential threats. Pollution from surface runoff associated with continued urbanization in the Huntsville metropolitan area and emerging missions and infrastructure projects on Redstone Arsenal threaten cave life, including Spinanycta alabamensis , at all three cave systems ( Bearden et al. 2022; USFWS 2022). At present, Bobcat and Muddy caves receives little human visitation; however, Rockhouse Cave receives a high level of unauthorized visitation despite its closed status, which has led to substantial vandalism and accumulation of trash in many sections of the cave.

Remarks.

In many species of the subfamily Cubacubaninae , the area between the 3 rd legs and the base of the abdomen has very distinct sexual secondary characters. In Speleonycta ozarkensis , the tibia of third leg has a large bulge with three distinctly long, sclerotized, and curved macrochaetae ( Espinasa et al. 2014). Anelpistina mexicana ( Espinasa, 1991) has on the lateral sides of urosternum III an extension with the shape of a hook or spine. Many species of Anelpistina have an articulated appendage in urosternum IV and Prosthecina avita Espinasa, 2000 has both the hook of urosternum III and the appendages in urosternum IV. Interestingly, the presence or absence of these characters follows little phylogenetic predictability, and sister species may lack the character, but the character may be present in distantly related species. With the new species, a new sexual secondary character is described, the spine in urosternum I.

It appears that during reproduction, males in this group may use this part of the body. Evolution has developed a plethora of variable structures. All these structures include some type of chaeta. Sensory input during their interaction with females during courtship may be involved. Unfortunately, their reproductive behavior has yet to be described. Future research may resolve what is the function of all these intriguing structures.