The true generic identity of Mastigoproctus pelegrini Armas , 2000 : a new genus of Antillean whipscorpions ( Thelyphonida : Thelyphonidae )

A new monotypic genus is herein described for the Western Cuban endemic whipscorpion Mastigoproctus pelegrini Armas, 2000. Its morphology is strikingly different from all other species of Mastigoproctus Pocock, 1894, but its generic placement remained unchallenged so far. Sheylayongium gen. n. is diagnosed from all other Mastigoproctinae Speijer, 1933 by a combination of several morphological characters of both sexes, e.g., high reduction of pedipalp armature and sexual dimorphism, carapace carination, unusual modification of sternite V, and female spermathecal structure. Its single species is thoroughly illustrated with high-resolution, full-color photographs, its geographical distribution is revised and updated, and new data are given on its natural history.


Introduction
In his rather succinct revision of the Cuban whipscorpions, Armas (2000) described Mastigoproctus pelegrini from the western part of the archipelago, with populations recorded from the two main islands: Cuba (former Pinar del Río Province, now including also Artemisa Province) and Isla de Pinos (Isla de la Juventud Special Municipality).In that moment, Mastigoproctus Pocock, 1894 was the single genus recognized to occur in the Greater Antilles.
During the last 15 years, several other American genera have been described or resurrected, involving either explicit or implicit redefinitions of the generic diagnosis of Mastigoproctus, see e.g.Armas & Víquez (2005), Víquez & Armas (2005, 2006), Huff et al. (2008), Haupt (2009) and Barrales-Alcalá et al. (2018).Nevertheless, the original generic assignment of M. pelegrini remained unchallenged, despite being morphologically quite distinct from all other Antillean and most continental members of Mastigoproctus, something already noticed even in its original description (Armas, 2000: 4).
With the aim to define the correct generic position of M. pelegrini, the present author undertook with some collaborators an intensive schedule of field trips, complemented with the revision of the complete whipscorpion collections of the main Cuban research institutions and museums.Such effort contributed more than 100 specimens from across its entire geographical range and their examination confirmed the initial supposition that M. pelegrini cannot be kept in its current generic assignation.The main objective of the present paper is to describe a new genus to accommodate this peculiar species, thoroughly illustrated with full-color photographs (including the first images of male and female genitalia).In addition, its geographical distribution is revised and updated, and new data are given on its natural history.

Material and Methods
Specimens were studied, measured and photographed under an AmScope SM-1T-PL LED trinocular stereo microscope, equipped with a 20X calibrated line scale for measuring.Unless otherwise noted, all photographs were taken with a Nikon Coolpix S8100 digital camera; microscopic shots were taken by manually attaching the camera to the upper ocular tube of the microscope.High-resolution images were processed with Adobe Photoshop CS5, only for contrast and brightness optimization, background cleanup and plate composition.
Distribution maps were constructed in Mapinfo Professional ver.10, using precise locality coordinates taken in situ with a portable GPS device (Datum WGS84) or extracted from 1:25 000 militaryreference cartographic maps.The literature cited herein is not an exhaustive compendium for each taxon, but a selection of the sources more relevant to the subject of the present paper: original descriptions, redescriptions and those dealing with taxonomy or contributing important information of ecology and geographical distribution.
Specimens studied herein are preserved in ethanol 80% and deposited in the following repositories: Instituto de Ecología y Sistemática, Havana, Cuba (IES) and personal collection of the author (RTO).
Abdominal sternites (fig.4b) undivided, II unmodified (only slightly bulky in adult male), III and V highly modified (see below for each sex).Flagellum (fig. 1) medium-sized, with 30-38 flagellomeres and with whip organs well developed, in ventrobasal location.Male: pedipalp trochanter with spines blunt, AS weak to vestigial; femur with dorsal internal tooth vestigial, ventral internal tooth small; patella and tibia with dorsal apophysis almost smooth on both edges.Sternite III with median area raised, triangular, whitish, densely setose and fenestrate; V with a large, oval to round, very densely setose (tufted) median depression.Genitalia (fig.5a): standard for Mastigoproctinae.Female: pedipalp trochanter with spines sharp, AS strong; femur with dorsal internal tooth small, ventral internal tooth moderate; patella and tibia with dorsal apophysis serrate on both edges.Sternite III with median area slightly raised, triangular, translucent and sparsely setose; V medially with a small, oval to drop-shaped, sparsely setose (not tufted) median depression.Genitalia (figs.5b-c): single pair of seminal receptacles, each shaped as a baby's bottle and with two very different parts: a basal half membranose, translucent, tubular and very short, plus a distal half highly sclerotized, very dark and nipple-shaped, with single apical bulb kidney-shaped, much narrower than base, about as wide as neck and curved backwards to outwards.evenly convex to tectiform, but always lacking such furrow in Mastigoproctus.

New records for
Ecological Notes.According to the personal observations of the present author, label data of the examined specimens and published literature, Sheylayongium pelegrini comb.n. typically occurs in limestone areas of karstic relief, covered by well-preserved semicaducifolious and evergreen forests (fig.7).This kind of landscape is abundant in cave formations, where this species frequently occurs as a typical troglophile.It ranges from the coast through low mountains under 500 m above sea level (fig.8).It digs shallow scrapes and short burrows under rocks, logs and other surface debris (figs.6d-f), sometimes also inside fallen rotten logs and inside holes and cracks of rocky substratum and boulders, especially if filled at least partially with humus and leaf litter.Early-instar juveniles are common also inside leaf litter, mainly accumulated at base of trees, boulders and cliffs.Late-pregnant females and next-to-molt juveniles always lock up themselves to undergo the entire process in the bottom of the burrow, inside a totally sealed oval chamber (fig.6f).
Females carrying litter (figs.6d-f) were found by the author in April and May, just at the transition period from dry to rainy season.All of them that were stored alive became stressed and ate all their newborn, within the first hour after being captured.As expected, remarkably higher numbers of second-instar juveniles (= recruitment), were found in June and July.
In western Isla de Pinos, this species digs deeper burrows in siliceous sandy soils, vegetated with mixed savannah/pine forest (Armas, 2000).
Under natural conditions, it preys upon smaller arthropods, especially millipedes (figs.6c-f).Cannibalism seems frequent in at least one cave population (Teruel & Rodríguez-Cabrera, 2014).See additional information in Armas (1987Armas ( , 2000)).Remarks.Amongst the six other whipscorpion genera currently recognized to occur in the Western Hemisphere, Sheylayongium gen.n. is clearly related on morphological grounds most closely to Mayacentrum and Ravilops, especially the latter.It is only distantly related to Mastigoproctus, to which essentially the single linking character is the presence of well-defined carapacial anterolateral carinae.
Three of the characters diagnostic for Sheylayongium gen.n. are remarkable: the longitudinal furrow all along the sternum, the setose median depression on sternite V and the structure of female genitalia.These most likely represent autapomorphies, because all are unique to this genus inside the whole Mastigoproctinae.It is noteworthy to mention here that a similar setose median depression on male sternite V is diagnostic for Ginosigma Speijer, 1933, but this South-East Asian genus is a typical member of the separate subfamily Thelyphoninae Lucas, 1835, which implies a clear convergence instead of synapomorphy.Also, a sternal longitudinal furrow was described by Huff & Prendini (2009) in the single African whipscorpion Etienneus africanus (also a member of this subfamily), but the figure 5b of that paper depicts it very different in shape and thus, it is apparently not homologous to the one present in Sheylayongium gen.n.
The drawings of the cheliceral movable finger published by Armas (2000: figs.1d-e) are absolutely wrong in all essential details, i.e., shape, curvature, thickness and sharpness of the finger, but especially the depicted absence of the outer basal notch and inner setation.For the present paper, both cheliceral movable fingers were carefully studied in more than 50 specimens from across the entire distributional range of Sheylayongium pelegrini comb.n., and this structure proved invariably and significantly different, as photographically shown herein (fig.5d).
On the other hand, two locality records published by Armas (2000Armas ( , 2013) ) have toponymical errors that are corrected accordingly: 1. "Cueva Oscura, Los Portales, San Diego de los Baños" (Armas, 2000: 4;Armas, 2013: 93).It is actually located in southern Guane Municipality, more than 80 km northeast of San Diego de los Baños Municipality.This cave has been well known to speleologists and general collectors for more than 50 years.2. "Hoyo de Fanías, Minas de Matahambre" (Armas, 2000: 4-5;Armas, 2013: 93).The correct toponym is Hoyo de Fanía and is actually located in western Viñales Municipality.It is a collapsed pit in Santo Tomás Cave System and has been well known to speleologists and general collectors for more than 50 years.Moreover, Armas (in Teruel & Rodríguez-Cabrera, 2014: 115) tentatively recorded this species from an undisclosed locality in Mayabeque Province (later, Luis F. de Armas himself personally communicated to the present author that it is Somorrostro, in San José de las Lajas Municipality).Such site is well outside the confirmed distribution of Sheylayongium gen.n. and thus, must be confirmed before accepted.Nevertheless, the voucher specimen is unfortunately missing from the IES collection: it was not found there by the present author during repeated, thorough revisions of its entire whipscorpion collection.
All new records listed above for Sheylayongium pelegrini comb.n. are supported by specimens collected mostly by the author and deposited in RTO collection.Complete data will be given elsewhere, in a forthcoming taxonomic revision of the genus (R. Teruel, in preparation).

Fig. 6 .
Fig.6.Live adults of Sheylayongium pelegrini comb.n., photographed in their natural habitat: a-b) male (a) and female (b) from Base de Campismo "Dos Hermanas", Viñales, Pinar del Río (see male largely covered with mud and with two foretic mites on tergite IV, as usual for this burrowing species during rainy season); c) male eating a millipede at Cañón del río Santa Cruz, San Cristóbal, Artemisa (photo courtesy Tomás M. Rodríguez-Cabrera); d) female with first-instar litter at Sierra La Guasasa, Viñales, Pinar del Río; e-f) female with first-instar litter at Sierra de San Carlos, Minas de Matahambre, Pinar del Río, outside (e) and inside (f) its burrow constructed under a large rock, see also food remains (wasp wings, beetle elytra, snail shells and millipede segments) cast aside burrow.