Microtityus (Parvabsonus) minimus Kovařík et Teruel, 2014

Kovařík, František & Teruel, Rolando, 2014, Three new scorpion species from the Dominican Republic, Greater Antilles (Scorpiones: Buthidae, Scorpionidae), Euscorpius 187, pp. 1-27 : 1-10

Microtityus (Parvabsonus) minimus Kovařík et Teruel ,

sp. n.

( Figures 1–26; Table 1) http://zoobank.org/urn:lsid:zoobank.org:act:90ABA6

09-AE7E-4C66-9EF7-D9C3C024606D

TYPE LOCALITY AND HOLOTYPE DEPOSITORY. Dominican Republic, Azua Province, Las Charcas Municipality, El Número, 18°21'16.8"N 70°30'55.3"W, 167 m a. s. l., RTOC.

TYPE MATERIAL. Dominican Republic, Azua Province, Las Charcas Municipality, El Número , 18°21'16.8"N 70°30'55.3"W, 167 m a. s. l., 6. III.2014, leg. R. Teruel, F. Kovařík et P. Kindl, 1♂ holotype ( Fig. 23, RTOC) 1♂ paratype ( Figs. 1–2, 5, 10, 16–17, FKCP) 1♀ paratype ( RTOC); same data except 15. III.2014, 3♂ 7♀ paratypes ( RTOC) 5♀ paratypes ( Figs. 3–4, 6–9, 11–15, 18–22, FKCP) .

ETYMOLOGY. The selected name is a Latin adjective that alludes to the extremely small adult size of this species, see remarks below.

DIAGNOSIS. Adult size very small (males 9–10 mm, females 11–12 mm) for the genus. Coloration pale yellow to yellowish brown, moderately spotted with blackish brown all over the body and appendages, tergites without clearly defined longitudinal dark bands, pedipalp hand immaculate (males) to vestigially spotted (females), fingers blackish with yellowish tips, metasomal segment V and telson only slightly more reddish; in general, coloration in males is paler and less densely spotted. Pedipalps neobothriotaxic (femoral trichobothrium d 2 absent), fixed and movable fingers with 8–9 principal rows of denticles. Sternites IV–V with two carinae, VI–VII with four; posterior margin of III widely convex, with the smooth patch large, subtriangular, flat, and not protruding beyond margin; V with the smooth patch moderately large, cordiform and bulky (males) or very small, fusiform, and flat (females). Metasoma moderately short, with 10-10-8-8-5 complete carinae, most of which are sharply serrate to denticulate, segments II– IV dorsolateral carinae with 2–3 terminal denticles unevenly enlarged, all intercarinal spaces finely and densely granulose; segment V prismatic in cross-section, with ordinary carination and tegumentary sculpture. Telson short oval, vesicle minutely (males) to coarsely (females) granulose, subaculear tubercle moderate and irregular, aculeus as long as vesicle (males) or slightly shorter (females). Pectines with 10–11 teeth (mode 10) in males, 8–9 (mode 9) in females; basal plate in females slightly longer than wide, spatulate, and with posterior margin straight.

DESCRIPTION (adult male holotype unless otherwise noted). Coloration ( Fig. 23) base pale yellowish to yellow, densely spotted with blackish brown all over the body and appendages except on the ventral region, which is essentially immaculate. Chelicerae pale yellowish; manus reticulate with blackish brown all over, but with pattern becoming denser and darker distally: fingers with basal half deeply infuscate. Pedipalp femur yellow, sparsely spotted with blackish brown on all surfaces except ventral, which is essentially immaculate; patella yellowish, very densely spotted with blackish brown on all surfaces except ventral, which possesses spots only in the distal half; chela pale yellow, with hand immaculate, fingers blackish with distal one-third yellowish. Carapace symmetrically and very densely spotted with blackish brown (most spots are interconnected), with frontal lobes essentially immaculate but separated by a large blackish spot; tergites densely spotted with blackish brown, but without clearly defined pattern of longitudinal bands; venter essentially immaculate, sternum with a wide, discontinuous transverse blackish stripe. Legs yellowish, becoming progressively paler distally, and with internal surface immaculate except on basitarsi; coxa and trochanter essentially immaculate yellow; femur and patella yellowish, with a single large, irregular blackish spot than surrounds dorsal, external, and ventral surfaces; basitarsi each conspicuously annulated: basal half blackish brown, distal half pale yellowish; telotarsi immaculate whitish. Metasoma pale yellowish, sparsely spotted with blackish brown on distal half of every segment, giving an irregularly annulated appearance; spots become progressively larger and denser towards segment V, which has distal half densely spotted; dorsal surface on I–IV with a large, arrowhead-shaped blackish spot medially; telson vesicle essentially immaculate yellowish, aculeus immaculate, with the distal two-thirds dark reddish brown.

CHELICERAE ( Fig. 16, male paratype). With dentition typical for the genus. Tegument smooth and shiny, weakly granulose distally on manus.

CARAPACE ( Fig. 16, male paratype). Slightly wider than long, markedly triangular. Anterior margin very narrow, deeply bilobed. Carinae: anterior median, lateral ocular, central median and posterior median granulose, superciliary subgranulose, other carinae obsolete to absent. Tegument very finely and densely granulose, with many coarse granules scattered. Median eyes separated by slightly more than one ocular diameter; three pairs of lateral eyes, which are all much smaller than median eyes.

MESOSOMA ( Figs. 16–17, male paratype). Tergites with the same sculpture as on carapace; I–VI with three longitudinal carinae, which are granulose sharply projected beyond the posterior margin, VII with five serrate longitudinal carinae. Sternum type 1, pentagonal, wider than long. Pectines reaching coxa-trochanter joint of leg IV; tooth count 10/10, fulcra very well developed; basal middle lamella slightly enlarged, angulose; basal plate unmodified, about as long as wide, and with posterior margin essentially straight. Sternites III–VI with round to very short-oval spiracles and a narrow, smooth to subgranulose longitudinal carina along midline of IV– VII; III with posterior margin strongly convex, lateral areas very shallowly depressed and essentially smooth, and with the smooth patch large, subtriangular, flat, and not protruding beyond posterior margin; IV–VI coriaceous to finely granulose, with coarser granules scattered; VII finely and densely granulose; V with posterior margin essentially straight and the smooth patch moderately large, cordiform, slightly longer than wide, translucent, and bulky, essentially not protruding from margin of sternite; IV–V without carinae, VI with two, VII with four, all granulose.

METASOMA AND TELSON ( Figs. 5 and 10, male paratype). Metasoma with intercarinal tegument finely and densely granulose, with many coarser granules scattered; segments I–II with ten complete carinae, II–IV with eight (even though lateral supramedian carinae are indicated by irregular granulation), V with five, all sharply serrate to denticulate, dorsolateral carinae on I–IV with 2–3 terminal denticles unevenly enlarged and very sharp. Telson vesicle short-oval, coriaceous with small granules scattered, and with a granulose ventromedian carina that abruptly rises into the subaculear tubercle, which points towards the basal third of the aculeus and is moderately-sized, irregularly conical, essentially smooth, and possesses two vestigial dorsal granules; aculeus as long as vesicle, sharp, and evenly curved.

LEGS. Legs with all carinae finely serrate; intercarinal tegument very finely and densely granulose.

PEDIPALPS ( Figs. 1–2, male paratype). Neobothriotaxic A-α (femoral d 2 absent). Femur with five serrate carinae; intercarinal tegument coriaceous to finely granulose, with coarser granules scattered; internal surface with the four i trichobothria surrounding a large, truncate spur. Patella with seven serrate carinae; intercarinal tegument with the same granular sculpture as on femur, but finer; internal surface with granules becoming progressively larger distally. Chela oval and much narrower than patella; hand with nine finely serrate carinae, intercarinal tegument very finely and densely granulose; fingers without basal lobe/notch combination, fixed finger with 9/9 principal rows of denticles, movable finger with 8/8 plus apical subrow composed by four granules aligned similar to principal rows.

FEMALE ( Figs. 3–4, 6–9, 11–15, 18–22; Tab. 1). Similar to the male, but sexual dimorphism is evident by: 1) size larger; 2) color pattern somewhat darker and more densely spotted; 3) genital papillae absent; 4) mesosoma remarkably wider, with sides convex; 5) pectines smaller, narrower, with lower tooth counts, and with basal plate longer than wide, spatulate; 6) pedipalps and metasoma with segments slightly shorter and wider; 7) sternite V with the smooth patch much smaller, fusiform, flat, and with a median suture.

VARIATION. The size differences among adults are so small (directly correlated to the minuteness of this scorpion), that a clear-cut recognition of size classes is not reliable. Nevertheless, there are probably two size classes in each sex; inside each class, males are consistently smaller than females ( Tab. 1).

Count of teeth per pecten was also little variable: 10 (n=8) and 11 (n=2) in males, 8 (n=4) and 9 (n=22) in females. The number of principal rows of denticles was almost constant too: nine and eight in fixed and movable fingers, respectively; a few specimens had eight and seven due to poorly defined basalmost rows.

AFFINITIES. Only two other Hispaniolan species lack femoral trichobothrium d 2: Microtityus paucidentatus Armas et Marcano, 1992 , and M. reini Armas et Teruel, 2012 . The former is known only from a single locality in the southern slope of the Sierra de Neiba (Independencia Province, roughly 100 km to the west of El Número), and is easy to distinguish from M. minimus sp. n. by: 1) size larger (male 13 mm, female 16 mm); 2) color pattern darker and much more densely spotted; 3) pectinal tooth count higher (male 11/11, female 9/10); 4) metasoma slightly longer and less robust; 5) male sternite V with the smooth patch much wider and shorter.

The most similar morphologically is actually M. reini , which occurs in the southern foothills of Cordillera Central (Peravia Province, about 25 km east of El Número), and can be unequivocally separated on the basis of the following characters (females only, as males are unknown): 1) size 13–14% larger (13–15 mm); 2) coloration basically darker, but with the spots lighter (body and appendages brownish orange, patterned with medium brown); 3) basal pectinal plate shorter, trapezoidal, and posteriorly narrower; 4) sternite III with posterior margin widely bilobed, with a median notch.

DISTRIBUTION ( Fig. 26). Known only from the type locality, in the southernmost foothills of the Cordillera

Central mountain range, in southern Dominican Republic.

ECOLOGICAL NOTES. This species lives in subcoastal desert scrub on gypsum-sandy soil, at an elevation of 160–170 m a. s. l. ( Fig. 24). All specimens were collected during diurnal searches, hanging to the underside of small limestone rocks half-buried in the dry leaf litter of thorny shrubs and cacti, at the base of hills ( Fig. 25). As observed previously in a few members of the genus, when the rocks were turned the individuals remained still but started to run very quickly after 10–20 seconds or at the slightest touch.

Other scorpions that occur at this locality are the scorpionid Cazierius politus (Pocock, 1898) , and the buthids Centruroides bani Armas et Marcano, 1987 , and Rhopalurus princeps (Karsch, 1879) . All of them occur syntopically under rocks with Microtityus minimus sp. n., but Centruroides bani is also found under dead barks of shrubs and trees, both standing and fallen.

All females were late pregnant when collected, with embryos clearly visible through sternites and pleural membranes. Seven were kept alive and gave birth during the first month in captivity ( Fig. 20); the litters consisted of 1, 2, 2, 3, 3, 4, and 5 newborn, and the first instar lasted for 4–6 days. Also, five of the 15 individuals collected on March 15, 2014 (two males and three females) were subadults and showed obvious signs of being about to carry out their final ecdysis; all of them were kept alive and molted successfully into perfect adults within 5–12 days, without need of being fed.

REMARKS. Despite the tiny size, maturity of the specimens herein declared as adults was clearly demonstrated: captive males mated and produced spermatophores, and females gave birth. Thus, M. minimus sp. n. is the smallest confirmed scorpion; a few other similarly sized (10 mm or less) specimens of the genera Microcharmus Lourenço, 1995 and Typhlochactas Mitchell, 1968 have been alleged to be adults (e. g., Sissom, 1988; Lourenço et al., 2006; Vignoli & Prendini, 2009) but their maturity, although apparent and probably real, has been never demonstrated. Figure 20 shows the smallest scorpion female (total length 11.4 mm) photographed with the newborn.

COMPARATIVE MATERIAL EXAMINED.

Microtityus paucidentatus Armas et Marcano, 1992 Dominican Republic, Bahoruco Province, Neiba Municipality, Sierra de Neiba, Apolinar Perdomo , Segundo Paso , 150 m a. s. l., 3.X.1987, leg. L. F. de Armas, A. Abud et P. Rivera, 1♀ holotype (IESC-3.2815) 1♂ paratype ( IESC) .