Microtityus (Parvabsonus) borincanus 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 : 2-5

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

Figures 1–3 , 6–7

http://zoobank.org/urn:lsid:zoobank.org:act:19B3B4 13-132C-4D7C-AA43-0B6392175B6D

TYPE DATA. ♀ holotype (to be deposited in RTO) : Puerto Rico, Sabana Grande Municipality, Barrio Susúa, Susúa State Forest , 18°05'34"N 66°54'32"W, 22 November 2013, leg. M. J. Rivera.

DIAGNOSIS. Adult size medium (17 mm) for the genus. Coloration yellowish brown, with a very dense pattern of blackish spots all over the body and appendages, metasomal segment V and telson slightly more reddish, tergites without clearly defined longitudinal dark bands, pedipalp fingers blackish with yellowish tips. Pedipalps orthobothriotaxic (femoral trichobothrium d 2 present), fixed and movable fingers with 10 principal rows of denticles, basal lobe/notch combination absent. Sternite V with the smooth patch small and teardrop-shaped. Metasoma moderately slender, 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 irregular, aculeus shorter than vesicle. Pectines with 10/10 teeth, basal plate conspicuously longer than wide and spatulate.

ETYMOLOGY. The selected name is a Latinized adjective taken from one of the two Spanish words used to name the people native to the island of Puerto Rico, whose ancient Taino name was "Borikén", and which modern variant is "Borinquen". It highlights the occurrence of this species here, a long awaited discovery among scorpiologists but so far unaccomplished.

DISTRIBUTION ( Fig. 6 ). Known only from the type locality, in southwestern Puerto Rico. It represents one of the few serpentine outcrops of the island, characterized by high levels of plant endemism (Cedeño- Maldonado & Breckon, 1996).

DESCRIPTION (female holotype). Coloration ( Figs. 1 , 3 ) base yellowish brown, very densely spotted with blackish brown all over the body and appendages, including the ventral region. Chelicerae pale yellowish, with distal margin of manus and basal half of fingers deeply infuscate. Pedipalp femur very densely spotted with blackish brown on all surfaces except ventral, which it is essentially immaculate; patella very densely spotted with blackish brown on all surfaces except ventral, which possesses spots only in the distal portion; chela with hand essentially immaculate, only a few vestigial spots are present on external surface, fingers blackish with yellowish tips. Carapace symmetrically and densely spotted with blackish brown, but with frontal lobes almost immaculate; tergites densely spotted with blackish brown, but without clearly defined pattern of longitudinal bands; venter very densely spotted with blackish brown all over leg coxae, sternum, genital operculum, pectines and sternites, but with a thin yellowish strip along midline of sternites III–VI. 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 spotted with blackish brown on all surfaces, spotted pattern becoming somewhat denser and darker distally in each segment; segments IV–V and telson slightly more reddish than I– III; telson vesicle densely spotted with blackish brown, fainter on distal half; aculeus immaculate, with the distal half blackish brown. Carapace ( Fig. 2b ) 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. 2a ) with the same granular sculpture as on carapace; I– VI with three longitudinal carinae, which are granulose and sharply projected beyond the posterior margin of every tergite, VII with five serrate longitudinal carinae. Chelicerae ( Fig. 2a ) with dentition typical for the genus, tegument smooth and shiny. Pedipalps ( Fig. 2a ) orthobothriotaxic A-α (femur with d 2). Femur with five serrate carinae, intercarinal tegument coriaceous to finely granulose, with coarser granules scattered, internal surface with the four i trichobothria surrounding a spur of moderate size (smaller in left pedipalp). Patella with seven serrate carinae, intercarinal tegument with the same granular sculpture as on femur, internal surface with 2–3 slightly larger granules. Chela oval and narrower than patella; hand with nine finely serrate carinae, intercarinal tegument coriaceous to finely granulose; fingers without basal lobe/notch combination, fixed finger with 10/10 principal rows of denticles, movable finger with 10/10 plus apical subrow composed by four granules aligned similar to principal rows (missing in right finger). Legs with all carinae serrate to granulose; intercarinal tegument coriaceous to finely granulose, with coarser granules scattered. Sternum ( Fig. 2c ) type 1, subtriangular. Pectines ( Fig. 2c ) about half the length of leg IV coxa. Tooth count 10/10, fulcra very well developed. Basal middle lamella slightly enlarged, oval. Basal plate longer than wide, not spatulate, with posterior margin narrowly convex. Sternites ( Fig. 2c ) 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, teardrop-shaped, 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. 1 , 2d ) 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 shiny, with a weakly subgranulose ventromedian carina that abruptly rises into the subaculear tubercle, which points towards the tip of the aculeus or slightly beyond, and is moderately-sized, irregularly conical, essentially smooth, and possesses two vestigial dorsal granules; aculeus shorter than vesicle, very sharp, and evenly curved.

COMPARISONS (adult female only). This species closely resembles Microtityus virginiae Armas, 1999 (from Sierra de Neiba in southern Hispaniola) as both share a unique combination of characters that unequivocally distinguish them both from the remaining members of the subgenus Parvabsonus : medium size, overall coloration very dark, metasoma slender, subaculear tubercle ventrally not serrate, and low pectinal tooth counts. But the latter can be easily distinguished from M. borincanus sp. n. by: 1) pedipalp chela with hand very densely spotted and fingers not uniformly blackish, but also irregularly spotted; 2) pedipalp fingers with nine principal rows of denticles; 3) dorsolateral carinae on metasomal segments I–IV with terminal denticle only vestigially enlarged; 4) telson conspicuously more slender, with subaculear tubercle longer and sharper.

ECOLOGICAL NOTES. The holotype and single known specimen was found inside a rotten log lying on the ground. Other scorpions that occur at Susúa State Forest are the scorpionid Heteronebo portoricensis Francke, 1978 , and the buthids Centruroides griseus (Koch, 1845) , Tityus angelesae Santiago-Blay, 2009 , and Tityus obtusus (Karsch, 1879) ; of them, H. portoricensis and T. angelesae are soil-dwelling species, while the other two are more habitat-generalist and also occur on the vegetation.

Figures

Figure 1: Female holotype of Microtityus (Parvabsonus) borincanus, sp. n., entire dorsal and ventral views.

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 3: Female holotype of Microtityus (Parvabsonus) borincanus, sp. n., coloration in life.

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).

Figure 7: Two views of Susúa State Forest, habitat of Microtityus (Parvabsonus) borincanus.