Antillostenochrus eremita, Teruel & Rodríguez-Cabrera, 2019

Teruel, Rolando & Rodríguez-Cabrera, Tomás M., 2019, Two remarkable new species of Hubbardiidae Cook, 1899 (Arachnida: Schizomida) from eastern Cuba, Ecologica Montenegrina 20, pp. 40-54 : 42-46

Antillostenochrus eremita , sp. n.

Figs. 1–4 , 9 , 12 . Table I

Type data. CUBA: GUANTÁNAMO PROVINCE: Imías Municipality: Yacabo Abajo (20°03'16"N - 74°41'51"W, 12 msnm); 11/September/2015; R. Teruel, T. M. Rodríguez-Cabrera; 1♂ heteromorphic holotype ( RTO), 1♀ paratype subadult? ( RTO) .

Diagnosis. Adult size large for the genus (male 5.2 mm, female 4.6 mm). Coloration immaculate pale olivaceous, with chelicerae, pedipalps and flagellum slightly darker. Propeltidium with two pairs of dorsal setae; eyespots vestigial. Heteromorphic male: pedipalps slightly elongated and robust (0.56 times longer than body; length/depth ratio of trochanter, femur, patella, tibia and tarsus = 1.73, 2.30, 2.41, 3.50 and 4.00, respectively); trochanter lanceolate and apically produced into a flat conical projection; femur straight and with five pairs of ventral spiniform macrosetae; patella ventrally armed with 3–4 pairs of spiniform macrosetae; tibia ventrally with 4–5 triads of macrosetae (those of the ventroexternal row very large, thick and knife-shaped). Tergal setation: I (2), II (4), III (2), IV (2), V (2), VI (2), VII (2), VIII (6), IX (4), X (8), XI (8), XII (12). Flagellum lanceolate and slender (2.90 times longer than wide, 1.11 times wider than deep), with the dorsal dome narrow and flanked laterally by two large, deep, angulose depressions directly opposing two ventral pits of the same size, shape and depth, subdistal keel or pit absent; pedicel/bulb angled at about 170°. Homomorphic male: unknown. Female: slightly smaller and less slender. Pedipalps shorter and robust (0.53 times longer than body; length/depth ratio of trochanter, femur, patella, tibia and tarsus = 1.59, 1.51, 2.26, 3.06 and 3.00, respectively), with setation much weaker. Tergal setation: I (2), II (4), III (2), IV (2), V (2), VI (2), VII (4), VIII (6), IX (6), X (8), XI (8), XII (12). Flagellum cylindrical and long (6.14 times longer than wide). Spermathecae unknown (single available specimen apparently immature).

Description (heteromorphic male holotype). Coloration (fig. 1): immaculate pale olivaceous, slightly darker on chelicerae, pedipalps and flagellum due to heavier sclerotization. Eyespots translucent. Abdominal segment XII with posterodorsal area progressively darker distally due to heavier sclerotization.

Pedipalp (fig. 3a): slightly elongate (1.78 times shorter than body). Trochanter lanceolate (1.73 times longer than deep), compressed, straight, and apically produced into a flat conical projection slightly curved downwards; dorsal margin convex and bare; ventral margin convex, with 9–10 very long, spiniform macrosetae; inner surface with 3–4 spiniform setae arranged into a curved row, essentially parallel to ventral margin, internal spur medium-sized and located not too close to the dorsal margin. Femur fusiform, stout (2.30 times longer than deep), straight and not bent basally; dorsal margin convex, with 10–12 large spiniform setae arranged into a longitudinal row irregularly bifurcate distally; ventral margin shallowly convex, with five pairs of large, thick spiniform setae arranged into two parallel longitudinal rows (ventrointernal and ventroexternal). Patella club-shaped, stout (2.41 times longer than deep) and weakly bent basally; dorsal margin smooth, with about 15 rigid macrosetae irregularly arranged into three longitudinal rows; ventral margin with two rows of long, paired, thick spiniform macrosetae (four ventroexternals, three smaller ventrointernals), plus a single macroseta in subdistal position between both rows. Tibia subcylindrical, stout (3.50 times longer than deep), vestigially bent basally; dorsal margin with 18–20 variously sized setae, most of them sedose; ventral margin with three essentially parallel rows of long, rigid setae all along: the ventrointernal row with four setae (some plumose or sinuose), the ventromedian row with five setae (some plumose or sinuose), and the ventroexternal row with five setae (very large, thick and knife-shaped, distally longer and thicker except for the distalmost one, which is much longer but thinner). Tarsus digitiform, stout (4.00 times longer than deep), straight and densely covered with variously sized setae (most of them sedose); apical spurs asymmetric (outer longer). Claw moderately large, sharp and evenly curved.

Propeltidium (figs. 1a–b): with 1 + 1 apical and two pairs of dorsal setae (very short and rigid). Eyespots vestigial (very small and inconspicuous) and irregularly subtriangular to Y-shaped.

Mesopeltidia (figs. 1a–b): triangular, widely separated.

Metapeltidium (figs. 1a–b): entire and lacking any traces of subdivision or pale median band, crescentshaped.

Legs (figs. 1a–b): I attenuate, II–III slender. Leg IV femur short and moderately robust (2.54 times longer than deep), with anterodorsal margin angled at slightly less than 90°.

Abdomen (figs. 1a–b, 3b–c): slightly attenuate distally. Tergite I with two pairs of anterior microsetae, II with three pairs. Tergal setation: I (2), II (4), III (2), IV (2), V (2), VI (2), VII (2), VIII (6), IX (4), X (8), XI (8), XII (12); setae large and rigid, those on distal segments apically trifid. Segment XII with dorsoposterior pair of macrosetae large, thick and slightly curved downwards; posterodorsal process absent.

Flagellum (figs. 1a–b, 3b–c): narrowly spatulate and not depressed (1.11 times wider than deep), with pedicel/bulb angled at about 170°. Pedicel short and compressed (remarkably deeper than wide). Bulb in dorsal view narrow (2.25 times longer than wide), anterior margin almost straight, very acutely angled forwards (at about 40°) and gradually merging into pedicel, lateral margins almost straight, very acutely angled backwards (at about 40°) and steeply merging into the apex; bulb in lateral view narrow (1.71 times longer than deep), dorsally not flat and lacking any subdistal keel or pit, and ventrally angled at about 120°; dorsal surface medially with an oval dome-like protuberance flanked laterally by a pair of large, deep, subtriangular depressions directly opposing a pair of ventral pits of the same depth that continue anteriorly as a lateral pair of elongate, S-shaped furrows; dm 1 seta located on sub-basal position on bulb (just at 1/4 of bulb length), dm 4 in subdistal position (just at 3/4 of bulb length); apex paraboloid in dorsal view, truncate in lateral view.

Female (figs. 2, 4; table I). The single specimen available seems subadult (see below, in Remarks section), but non age-related sexual dimorphism is evident as follows. 1. Pedipalps without large, knife-shaped spiniform macrosetae on patella and tibia. 2. Tergites II–VII with setal formula 4 / 2 / 2 / 2 / 2 / 2. 3. Flagellum cylindrical and much narrower, with three flagellomeres and two annuli.

Comparisons. A. eremita sp. n. is very easy to distinguish from most other Cuban congeners by its uniform pale olivaceous coloration, i.e., the prevailing coloration in Antillostenochrus is pale yellowish body with dark orange to reddish pedipalps and chelicerae. Only Antillostenochrus alticola Teruel, 2003 and Antillostenochrus longior Teruel, 2013 diverge from this pattern by being greenish, but anyway are distinct: both are conspicuously darker and the former has pale brown pedipalps and chelicerae, besides lacking eyespots.

Apart from this, the tergal setation pattern in both sexes (tabs. I–III) unambiguously diagnoses this new species, especially for the great reduction in female counts. It is the least sexually dimorphic member of the genus for this character, e.g., the single species with females having less than 10 setae on tergites VI– VIII; all other Cuban congeners have 10–28 setae on these plates.

A third character diagnostic for A. eremita sp. n. is the sculpture of male flagellum: it is much more deeply carved than any other member of the genus, especially the dorsal submedian depressions and ventral submedian furrows, which are both much larger and deeper than in all other Antillostenochrus . Moreover, the flagellar setae are markedly thicker and more spiniform than in all other congeners.

Etymology. The selected epithet is a Latin noun that literally means "arid-dweller, hermit". It is used here in apposition and accurately reflects two peculiarities of the type-locality: its desertic condition and its isolation south of the Sagua-Baracoa mountains. All other Cuban congeners live in mesic to very humid forests of the northern watershed.

Distribution (fig. 12). This species is known only from the type-locality, enclaved in the arid southern coast of the Sagua-Baracoa Mountains.

Ecological notes (fig. 9). Both available specimens of A. eremita sp. n. were found together, hanging to the underside of a very large limestone rock semi-buried in the dry leaf litter over clay soil, under a tree isolated in the coastal desert scrub, at the base of a cliff. Yacabo Abajo is located roughly in the center of the most arid zone of Cuba (fig. 9a), which is traditionally called "the Guantanamo Semi-Desert".

It lives there syntopically with Rowlandius cf. marianae Teruel, 2003 , one specimen of which was found even under the same rock as the types. It seems to be highly localized and/or scarce: another search three days later in the same exact spot did not yield any schizomids and other additional attempts there and in other sites along the same coast have been unproductive as well.

Remarks. By the degree of pedipalp attenuation, the holotype of A. eremita sp. n. represents a class-1 heteromorphic, i.e., the least attenuated (see Teruel, 2015: 78–79).

The single female available seems subadult, as suggested by its smaller size and less sclerotized exoskeleton, especially pedipalps; nevertheless, it could be instead a small adult shortly after its last ecdysis. We chose not to dissect its spermathecae because this process would inevitably damage external structures that are crucial for an accurate species identification in this genus, such as the spination and setation of the body and appendages.

With this addition, all Cuban Antillostenochrus may be identified using the following key:

1 Eyespots absent. Female: tergites II–VII with setal formula 8 / 10 / 10 / 18 / 20 / 24. Distribution: El Toldo High Plateau, in southeastern Holguín Province .......................................................... A. alticola

- Eyespots variable in size and definition, but always present. Female: tergites II–VII with setal formula 4–6 / 2–4 / 2–8 / 2–12 / 2–14 / 4–22. Distribution: outside El Toldo High Plateau................ 2

2 Coloration essentially monochromatic: uniform greenish overall. Eyespots very small and inconspicuous. Female: abdominal segments X–XI with setal formula 8 / 8 .......................................... 3

- Coloration essentially bicolor: body pale yellowish, chelicerae and pedipalps dark orange to reddish brown. Eyespots variable in size, but always larger and distinct. Female: abdominal segments X–XI with setal formula 5 / 7 ..................................................................................................................................... 4

3 Coloration darker overall, deep green. Male: size smaller (4.4–4.7 mm); flagellum bulb much shorter, broader and flatter (length/width ratio = 1.46–1.48, width/depth ratio = 1.47), lanceolate in dorsal view, with the lateral depressions narrow and obliquely elongate. Female: tergites IV–VIII with setal formula 4 / 6 / 10 / 12 / 16. Distribution: northern mesic coast of central-eastern Cuba, at the border of Camagüey and Las Tunas Provinces....................................................................... A. longior

- Coloration lighter overall, pale olivaceous. Male: size larger (5.2 mm); flagellum bulb much longer, narrower and deeper (length/width ratio = 2.25, width/depth ratio = 1.11), spatulate in dorsal view, with the lateral depressions very wide and subtriangular. Female: tergite IV–VIII with setal formula 2 / 2 / 2 / 4 / 6. Distribution: southern arid coast of Guantánamo Province ................. A. eremita sp. n.

4 Male: flagellum bulb dorsally without lateral depressions. Female: tergite VI with 10 or 12 setae.... 5

- Male: flagellum bulb dorsally with two lateral depressions variable in size and depth, but always present. Female: tergite VI with 14 setae ...................................................................................................... 6

5 Male: size smaller (3.9–4.4 mm); flagellum bulb much shorter, broader and flatter (length/width ratio = 1.67, width/depth ratio = 1.29), lanceolate in dorsal view; tergites VIII–XII with setal formula 4 / 4/ 7 / 7 / 14. Female: tergites VII–VIII with setal formula 14 / 16 ................................. A. alejandroi

- Male: size larger (4.7–4.9 mm); flagellum bulb much longer, narrower and deeper (length/width ratio = 2.11, width/depth ratio = 1.00), spatulate in dorsal view; tergites VIII–XII with setal formula 6 / 4 / 5 / 5 / 16. Female: tergites VII–VIII with setal formula 22 / 22 ..................................... A. holguin

6 Male: size smaller (3.4–3.9 mm); flagellum bulb dorsally with the lateral depressions vestigial. Female: tergites III–IV with setal formula 2 / 4 ..................................................................... A. planicauda

- Male: size larger (3.9–5.7 mm); flagellum bulb dorsally with the lateral depressions well developed. Female: tergites III–IV with setal formula 4 / 8 ........................................................................................... 7

7 Male: flagellum bulb dorsally with an arcuate transverse carina between the dome-like protuberance and dm 4 seta; abdominal segments X–XII with setal formula 8 / 6 / 12 ....................................... A. anseli

- Male: flagellum bulb dorsally lacking any carina between the dome-like protuberance and dm 4 seta; abdominal segments X–XII with setal formula 7 / 7 / 14–16...................................................................... 8

8 Male: size much larger (5.6–5.7 mm); flagellum bulb longer and deeper (length/width ratio = 1.58, width/depth ratio = 1.25); tergite VIII with 2 setae, abdominal segment XII with 14. Female: size much larger (6.5–6.9 mm); tergite II with 6 setae, tergite V with 12. Distribution: between Baracoa and Maisí, in northeastern Guantánamo Province ............................................................ A. cokendolpheri

- Male: size much smaller (3.9–4.6 mm); flagellum bulb shorter and flatter (length/width ratio = 1.40, width/depth ratio = 1.47–1.67); tergite VIII with 6 setae, abdominal segment XII with 16. Female: size much smaller (4.3–4.6 mm); tergite II with 4 setae, tergite V with 8. Distribution: Gibara Range, in northwestern Holguín Province ................................................................................ A. gibarensis

Figures

Figures 1-2. 1 Adult male holotype of Antillostenochrus eremita sp. n., habitus: a) dorsal view; b) lateral view. 2 Subadult (?) female paratype of Antillostenochrus eremita sp. n., habitus: a) dorsal view; b) lateral view.

Figures 3-4. 3 Adult male holotype of Antillostenochrus eremita sp. n., close-ups: a) pedipalps, lateral view; b) abdominal segments IX–XII and flagellum, dorsal view; c) abdominal segments IX–XII and flagellum, lateral view. 4 Subadult (?) female paratype of Antillostenochrus eremita sp. n., close-ups: a) pedipalps, lateral view; b) abdominal segments VIII–XII and flagellum, dorsal view; c) abdominal segments VIII–XII and flagellum, lateral view.

Figures 9-11. 9 Ecological conditions at the type-locality of Antillostenochrus eremita sp. n.: a) overview of the area; b) detail, the types were found under the larger tree at center; c) exact finding spot, see the large rocks semi-buried at the tree base. 10 Ecological conditions at the type-locality of Troglocubazomus inexpectatus sp. n.: a) overview of the area; b) detail, see the cave entrance at bottom right; c) exact finding spot, the holotype was found under the rock turned-over at center. 11 Ecological conditions at the type-locality of Troglocubazomus orghidani included here for comparison: a) overview of the area; b) detail, the cave entrance is located at bottom left; c) exact finding spot, see the senior author in the moment of collecting a topotype.

Figures 12-13. 12 Map showing the geographical distribution of Antillostenochrus eremita sp. n. (red symbol) and the remaining Cuban populations of the genus (yellow symbols). Image frame = 450 x 195 km. 13 Map showing the geographical distribution of Troglocubazomus inexpectatus sp. n. (red symbol) and Troglocubazomus orghidani (yellow symbol). Image frame = 450 x 195 km.