Pseudocellus dissimilior, Teruel, 2018

Teruel, Rolando, 2018, Two remarkable new species of Pseudocellus Platnick, 1980 (Ricinulei: Ricinoididae) from eastern Cuba, Ecologica Montenegrina 19, pp. 73-88 : 75-78

Pseudocellus dissimilior sp. n.

Figures 1 –6, 13, 16, 18–19. Table I

TYPE DATA. CUBA: GUANTÁNAMO PROVINCE: El Salvador Municipality: Meseta del Guaso [Guaso Plateau]: Limonar; inside cave, no more data; 1♂ holotype , 1♀ paratype ( RTO).

ETYMOLOGY. The selected epithet is a Latin adjective that literally means "the most different". It obviously alludes to the remarkable distinction of this species from all other Cuban ricinulids.

DIAGNOSIS. Adult size moderately large for the genus (male 5.2 mm, female 5.4 mm). Coloration light reddish brown, essentially uniform; ocular spots whitish. Entire body and appendages covered with short to minute sedose setae. Body very robust: carapace slightly shorter than wide (length/width ratio 0.99 in male, 0.97 in female), abdomen stout-oval (length/width ratio 1.36). Appendages attenuate. Leg II slender (length/width ratio of femur 5.19 in male, 6.23 in female; of tibia 3.75 in male, 5.07 in female; of basitarsus 10.00 in male, 8.23 in female); femur cylindrical, vestigially swollen (male) or not (female); tibia moderately modified in male (vestigially swollen, internal surface conspicuously concave, armed with a weak prolateral apophysis and a retrolateral row of small denticles), slightly modified in female (not swollen, internal surface shallowly concave, armed with a pair of prolateral and retrolateral rows of minute denticles); basitarsus minutely denticulate on internal surface only. Cucullus, carapace, tergal plates and legs densely and evenly covered with fine granules. Median plate of tergites XI-XII widely trapezoidal (XI–XII much wider than long, XIII slightly wider than long), discal dome on XI only. Pygidium not notched.

DESCRIPTION (adult male holotype; figs. 1, 3, 5, 13, 18–19; tab. I). Coloration (fig. 1) reddish brown, without any discernible patterns, but slightly darker on carapace and legs II and paler on pedipalps and chelicerae. Eyespots translucent white. Cuticular granulation and denticulation much darker due to heavier sclerotization; pleural and articular membranes yellowish.

Cucullus (fig. 3; tab. I). Much shorter than wide (length/width ratio 0.68), markedly convex and densely covered with short to minute, curved, translucent sedose setae. Anterior margin markedly bilobed, with a deep median notch. Tegument finely and evenly granulose.

Carapace (fig. 3; tab. I). Slightly shorter than wide (length/width ratio 0.99), convex, densely covered with minute, curved, translucent sedose setae and with a deep median furrow all along. Anterior and posterior margins almost straight, lateral margins convex and convergent anteriorly. Eyespots very large, conspicuous and kidney-shaped. Tegument finely and evenly granulose (even over eyespots).

Abdomen (fig. 3; tab. I). Stout-oval (length/width ratio 1.36), densely covered with minute, curved, translucent sedose setae and with lateral margins conspicuously convex. Median plate of tergites XI–XIII trapezoidal, each with a pair of lateral furrows, with anterior margin shallowly sinuose, lateral margins subtly converging backwards and posterior margin shallowly bilobed; XI much wider than long (length/width ratio 0.63) and with a moderately raised dome on anterior half; XII much wider than long (length/width ratio 0.74) and flat; XIII slightly wider than long (length/width ratio 0.97) and essentially flat. Tegument finely and evenly granulose.

Pygidium (fig. 3; tab. I). Very short and wide, not notched and densely covered with minute, curved, translucent sedose setae. Tegument coriaceous.

Pedipalps (tab. I). Densely covered with minute, curved, translucent sedose setae. Tibia short, thick and markedly curved inwards; tegument very finely and evenly granulose, ventral surface with two widely spaced prolateral denticles. Tarsus long and slender; tegument smooth.

Legs (figs. 1, 5, 13; tab. I). Slender and densely covered with minute, curved, translucent sedose setae, tegument finely and evenly granulose. Leg I moderately long, internal surface of tibia with two long, parallel rows (prolateral and retrolateral) of minute denticles, distal half shallowly concave. Leg II long: femur cylindrical, round in cross-section and vestigially swollen (length/width ratio 5.19); patella short (length/width ratio 2.49) and slightly bent basally; tibia vestigially swollen (length/width ratio 3.75), internal surface with basal half not inflate and distal two-thirds conspicuously concave, with a weak prolateral apophysis (short, obtusely triangular) and two parallel rows (prolateral and retrolateral) of minute to small, sharp denticles; basitarsus very long (length/width ratio 10.00), slightly club-shaped, weakly curved upwards and with minute, sharp denticles on prolateral surface only. Leg III moderately long, copulatory organ depicted in figure 13. Leg IV moderately long.

FEMALE (paratype; figs. 2, 4, 6; tab. I). Very similar to male, with the following sexually dimorphic differences: 1) legs II slightly more slender, with internal surface of tibia lacking prolateral apophysis; 2) legs III lacking copulatory organ.

COMPARISONS. The very well developed eyespots (figs. 3–4, 19) make P. dissimilior sp. n. very easy to distinguish at first from all other Cuban described species, in which these structures are entirely absent.

Apart from this conspicuous character and as expected from its geographical occurrence, it clearly belongs in the first group defined by Armas (2017) to accommodate all species from eastern Cuba. It can be distinguished very easily from them all by the highly unusual combination of a very stout body with more slender appendages, as clearly seen in the following two examples:

1. The tergite XIII median plate is wider than long in P. dissimilior sp. n.: length/width ratio 0.97 in male, 0.96 in female. In all other eastern species, this proportion is always reversed: pooled length/width ratio 1.18–1.63 in males, 1.16–1.80 in females.

2. The male leg II femur and tibia are only vestigially swollen in P. dissimilior sp. n.: length/width ratio 5.19 and 3.75, respectively. In the other six species, both segments are conspicuously swollen: pooled length/width ratio 2.75–3.60 and 2.00–3.25.

Moreover, figure 19 herein shows a good comparison of the adult males of P. dissimilior sp. n. against those of all other eastern Cuban species.

DISTRIBUTION (fig. 18). This species is known only from the top of the Guaso Plateau (= Meseta del Guaso, about 450 m a.s.l.), in northern Guantánamo Province. The types were collected inside a cave whose name (if any) was not specified in the collection label.

ECOLOGICAL NOTES. The only data included in the collecting label is that both types were found inside a cave. The Guaso Plateau (fig 18) is a roughly east-to-west oriented limestone karstic massif, oval in shape (25 x 10 km), with a mean altitude of about 500 m a.s.l. and the highest summit at 862 m a.s.l. The ground is perforate by dozens of caves of various sized and elevations, some of them containing running rivers (fig 16c) and/or large bat colonies inside.

The vegetation was originally composed by a mosaic of semicaducifolious and evergreen forests (figs. 16a–b), but it has been severely affected by logging and largely replaced by crops (e.g., coffee, fruits, tubers and sugarcane) and pastures. The type locality (Limonar area) has exactly this same ecological conditions and lies at an altitude of 450 m a.s.l.

REMARKS. This species seems to be either extremely rare, or micro-localized: in an attempt to find additional specimens, the author and one skilled collaborator conducted a three-day collecting trip to the Limonar area in early April/2015, but no ricinulids were found despite intensive search that included three caves (one the large sinkhole of the Cuzco River, see fig. 16c herein). Nevertheless, it must be noted here that the ecological conditions were unfavorable due to a severe drought.

Figures

Fig. 1. Pseudocellus dissimilior sp. n., adult male holotype, full-body views: a) dorsal; b) ventral. Scale bar in millimeters. Fig. 2. Pseudocellus dissimilior sp. n., adult female paratype, full-body views: a) dorsal; b) ventral. Scale bar in millimeters.