Microtityus (Parvabsonus) santosi Teruel, Rivera et Sánchez, 2014

Teruel, Rolando, Rivera, Mel J. & Sánchez, Alejandro J., 2014, First record of the genus Microtityus Kjellesvig-Waering, 1966, from Puerto Rico, with description of two new species (Scorpiones: Buthidae), Euscorpius 180, pp. 1-11 : 5-10

Microtityus (Parvabsonus) santosi Teruel, Rivera et Sánchez , sp. n.

Figures 4–6

http://zoobank.org/urn:lsid:zoobank.org:act:5568BA 44-C675-4918-8CF4-4C89B601740C

TYPE DATA. ♀ holotype ( UPRM) : Puerto Rico, Culebra Municipality, Barrio Fraile, Culebrita Island , 18°05' 34"N - 66°54'32"W, August 31, 2013, leg. C. J. Santos.

DIAGNOSIS. Adult size small (13 mm) for the genus. Coloration light yellow, with a moderately dense pattern of dark brown spots all over the body and appendages; metasomal segment V and telson slightly paler and less spotted; tergites with three poorly defined longitudinal dark bands; pedipalp fingers dark brown with yellowish tips. Pedipalps orthobothriotaxic (femoral trichobothrium d 2 present), fixed and movable fingers with nine principal rows of denticles, basal lobe/notch combination absent. Sternite V with the smooth patch small and rhomboid. Metasoma moderately robust, with 10- 10-8-8-5 complete carinae, most of which are finely serrate, segments II–IV dorsolateral carinae with terminal denticle enlarged, all intercarinal spaces coriaceous to finely granulose. Telson oval, vesicle coriaceous, subaculear tubercle moderate and conical, aculeus about as long as vesicle. Pectines with 9/9 teeth, basal plate slightly wider than long and not spatulate.

ETYMOLOGY. We are pleased to name this species after Dr. Carlos José Santos Flores (Universidad de Puerto Rico, Recinto Mayagüez), who collected the holotype and kindly made it available for study to us .

DISTRIBUTION ( Fig. 6 ). Known only from the type locality, a tiny islet offshore Culebra Island in northeastern Puerto Rico .

DESCRIPTION (female holotype). Coloration ( Fig. 4 ) base light yellow, densely spotted with dark brown all over the body and appendages, remarkably less on the ventral region. Chelicerae pale yellowish, with distal margin of manus and basal half of fingers deeply infuscate. Pedipalp femur very densely spotted with dark brown on all surfaces except ventral, which it is immaculate; patella very densely spotted with blackish brown on all surfaces except ventral, which possesses spots only in the distal portion; chela with hand almost immaculate, only a few small to moderate dark spots are present on external surface, fingers dark brown with yellowish tips. Carapace symmetrically and densely spotted with dark brown, but with frontal lobes almost immaculate; tergites densely spotted with dark brown, with three poorly defined longitudinal dark bands; venter sparsely to moderately spotted with dark brown all over leg coxae, sternum, genital operculum, and sternites III– VI, VII very densely spotted except on lateral margins; pectines immaculate yellowish, basal plate with small spots. Legs with trochanter, femur and patella very densely spotted with blackish brown externally, sparsely spotted both dorsally and ventrally, but immaculate internally, tarsi each conspicuously annulated: basal half blackish brown, distal half pale yellowish. Metasoma densely reticulated with dark brown on all surfaces, spotted pattern not becoming denser or darker distally in each segment; telson conspicuously paler; telson vesicle sparsely spotted with brown, essentially immaculate on distal half; aculeus immaculate, with the distal half dark brown. Carapace ( Fig. 5b ) slightly wider than long, subtriangular. Anterior margin deeply bilobed. Carinae: anterior median, lateral ocular, central median and posterior median granulose, superciliary subgranulose, other carinae obsolete to absent. Tegument coriaceous to finely granulose, with coarser granules scattered. Median eyes separated by more than one ocular diameter; three pairs of lateral eyes, which are all much smaller than median eyes. Tergites ( Fig. 5a ) with the same granular sculpture as on carapace; I–VI with three longitudinal carinae, which are granulose and weakly projected beyond the posterior margin of every tergite, VII with five serrate longitudinal carinae. Chelicerae ( Fig. 5a ) with dentition typical for the genus, tegument smooth and shiny. Pedipalps ( Fig. 2a ) orthobothriotaxic A-α (femur with d 2). Femur with five serrate to crenulate carinae, intercarinal tegument coriaceous to finely granulose, with coarser granules scattered, internal surface with the four i trichobothria surrounding a spur of moderate size. Patella with seven serrate to granulose carinae, intercarinal tegument with the same granular sculpture as on femur, internal surface with one conspicuously larger granule. Chela oval and narrower than patella; hand with nine finely granulose to costate carinae, intercarinal tegument coriaceous to finely granulose; fingers without basal lobe/notch combination, fixed finger with 9/9 principal rows of denticles, movable finger with 10/10 and no apical subrow. Legs with all carinae serrate to granulose; intercarinal tegument coriaceous to finely granulose, with coarser granules scattered. Sternum ( Fig. 5c ) type 1, pentagonal. Pectines ( Fig. 5c ) about half the length of leg IV coxa. Tooth count 9/9, fulcra well developed. Basal middle lamella slightly enlarged, oval. Basal plate wider than long, not spatulate, with posterior margin widely convex. Sternites ( Fig. 5c ) with short-oval spiracles. Sternite III with the lateral areas shallowly depressed and essentially smooth; IV–VI coriaceous to finely granulose, with coarser granules scattered; VII finely and densely granulose. Posterior margin of V essentially straight, with the smooth patch small, cordiform, slightly longer than wide, translucent, and not bulky nor protruding from posterior margin of sternite; VI–VII with two pairs of granulose lateral carinae. Metasoma ( Figs. 4 , 5d ) with intercarinal tegument coriaceous to very finely and densely granulose, with coarser granules scattered; segments I–II with ten complete carinae, II–IV with eight, V with five, all sharply serrate, dorsolateral carinae on I–IV with terminal denticle conspicuously enlarged and very sharp. Telson vesicle oval, smooth and coriaceous, with a weakly subgranulose ventromedian carina that obtusely rises into the subaculear tubercle, which points towards the distal third of the aculeus and is moderately-sized, regularly conical, smooth, and lacks any dorsal granules; aculeus about as long as vesicle, very sharp, and evenly curved.

COMPARISONS (adult female only). This species possesses an autapomorphy that unambiguously distinguishes it from all other members of the subgenus Parvabsonus : the basal pectinal plate wider than long (actually very short), not spatulate, and with the posterior margin widely convex. The shape of this plate varies among the different species, but it is always longer than wide, spatulate, and with the posterior margin narrowly convex, straight, or concave.

Apart from this, at first sight it resembles Microtityus waeringi Francke & Sissom, 1980 (from the neighboring Virgin Islands) by its small size, overall coloration dark but not blackish, metasoma not particularly slender, and subaculear tubercle moderate and ventrally not serrate. But the latter can be easily distinguished from M. santosi sp. n. by: 1) pedipalp femur less densely spotted, and metasoma distally darker; 2) sternite V without smooth patch.

ECOLOGICAL NOTES. According to the collector (C. J. Santos Flores, personal communication), the holotype and single known specimen was found while sorting dry leaf litter taken directly from the ground, at an approximate altitude of 15 m a.s.l. The only other scorpion so far known from Culebrita Island is C. griseus , which occurs both in the soil and the vegetation.

General Comments

The present additions raise the number of Microtityus species known from the Greater Antilles to 22, all of them belonging to the subgenus Parvabsonus as recently redefined by Armas & Teruel (2012). Nevertheless, at least 10 undescribed additional taxa are already identified and being described from Cuba and Hispaniola (R. Teruel & L. F. de Armas, in preparation).

With the discovery of the two new species in both geographical extremes of Puerto Rico ( M. borincanus sp. n. in the southwest of the main island and M. santosi sp. n. in a satellite islet in the northeast), the possibility that the genus may be more widespread and diverse in this archipelago becomes quite real. The species of Microtityus typically have small and/or patchy distributions, which are strictly associated to particular landscape, vegetation or soil type, and allopatric speciation seems to have occur intensively in every territory where the genus is present, thus, there is no reason to assume Puerto Rico may be an exception to this clear pattern.

The three Microtityus species now known to occur at the Puerto Rican Insular Bank can be reliably distinguished from each other using the following key (based on females only, as no males are known from two of them):

1- Pectines with the basal plate very short, wider than long, not spatulate, and with posterior margin widely convex. Distribution: Culebrita Island ------------------ ------------------------------------------- M. santosi sp. n.

- Pectines with the basal plate longer than wide, spatulate, and with posterior margin narrowly convex or concave. Distribution: Puerto Rico or Virgin Islands ---------------------------------------------------- 2

2- Coloration very dark and densely spotted with blackish brown. Pedipalp fingers with ten principal rows of denticles. Basal pectinal plate with posterior margin narrowly convex. Sternite V with a small smooth patch. Distribution: southwestern Puerto Rico -------------------------------- M. borincanus sp. n.

- Coloration lighter and moderately spotted with medium to dark brown. Pedipalp fingers with nine principal rows of denticles. Basal pectinal plate with posterior margin concave. Sternite V without smooth patch. Distribution: Virgin Islands ------ M. waeringi

Figures

Figure 2: Female holotype of Microtityus (Parvabsonus) borincanus, sp. n.: a) pedipalps; b) carapace and anterior tergites; c) sternopectinal region and anterior sternites; d) metasomal segment V and telson, lateral view.

Figure 4: Female holotype of Microtityus (Parvabsonus) santosi, sp. n., entire dorsal and ventral views.

Figure 5: Female holotype of Microtityus (Parvabsonus) santosi, sp. n.: a) pedipalps; b) carapace and anterior tergites; c) sternopectinal region and anterior sternites; d) metasomal segment V and telson, lateral view.

Figure 6: Distribution of the genus Microtityus in the Greater Antilles (above), and the Puerto Rican Microtityus (Parvabsonus) borincanus, sp. n. (1) and Microtityus (Parvabsonus) santosi, sp. n. (2).