Pseudochthonius lubueno, Assis & Schimonsky & Gallão & Bichuette, 2023

Assis, Leonardo de, Schimonsky, Diego Monteiro von, Gallão, Jonas Eduardo & Bichuette, Maria Elina, 2023, Contribution to the knowledge of Brazilian troglobitic Pseudoscorpiones (Arachnida): description of Pseudochthonius lubueno sp. nov. (Chthoniidae) from Serra do Ramalho karst area, state of Bahia, Brazil, Zoologia (e 22048) 40, pp. 1-11 : 4-6

Pseudochthonius lubueno sp. nov.

Fig. 3

https://zoobank.org/ 01864229-28C0-4FB4-B705-02A200D8AD89

Type material. Holotype male. BRAZIL: Bahia, Caatinga province, Serra do Ramalho karst area, Serra do Ramalho , Gruna da Altina cave ; 13°33’39.2”S, 43°45’10.3”W; 27.XI.2015; Bichuette ME, Gallão JE leg.; LES 0014723 . Paratype female, same data as holotype ; LES 0014724 .

Diagnosis. Pseudochthonius lubueno sp. nov. bears similarities to the troglobitic species of Pseudochthonius , P. strinatii , P. biseriatus , P. ramalho , P. olegario , P. diamachi , P.koinopoliteia and P. pali , due to it is a moderately sized troglomorphic species with elongate appendages and absence of body pigmentation. However, it differs in other characters and can be identified by the following combination: P.lubueno sp. nov. has the rallum with five blades (nine in P. biseriatu s, 7 in P. olegario , seven in P. diamachi , seven in P. koinopoliteia , and seven in P. pali ); one distal isolate teeth in movable finger of chelicera (isolated teeth in booth fingers in P. diamachi ); has epistome with anterior margin slightly serrate on the sides and distinctly serrate with median denticles in the middle (in P. ramalho , the anterior margin distinctly serrate with median denticles larger than lateral ones); 1.10 male, 1.24 female body length (1.55 male, 1.45 female in P. ramalho , 1.20 male, 1.58–1.60 female in P. olegario , 2.02–2.33 female in P. diamachi , 1.69 male, 1.7–1.95 female in P. koinopoliteia and 1.33 male, 1.70 female in P. pali ); eyes or eyespots absent (eyespots present in P. strinatii and P. ramalho ); posteriorly constricted carapace (in P. koinopoliteia carapace rectangular practically without posterior constriction); without microdenticles on the fixed pedipalpal finger (2 present in P. ramalho ), 30–31 teeth on the fixed chelal finger (41 in P.diamachi , 38 in P.koinopoliteia , and 34–39 in P. pali , and heterodentate chelal teeth on the fixed finger (homodentate in P. strinatii ); trichobothrium et near to dx and it (et distal to it in P. diamachi and P. koinopoliteia ). Concerning the position of trichobothrium ist, closer to esb than to est, P. lubueno sp. nov. has the ratio ist–est/ist–esb = 1.90 (3.0 in P. strinatii , 1.98 in P. ricardoi , 1.22 in P. gracilimanus , 4.71 in P. ramalho , 1.02 in P. diamachi , 0.68 in P. koinopoliteia , 2.46 in P. pali , 2.37 in P. tuxeni , 2.34 in P. brasiliensis and 2.06 in P. orthodactylus ); 3 setae on tergites I–II (2 setae in P. biseriatus , 2–4 in P. diamachi ); coxa I with 2 and coxa II with 4–5 coxal spines (in P. biseriatus , I 5+3–4 and II 5+5–6, in P. ramalho I 3-5 and coxa II 5–3, in P. diamachi I 3–5 and II 4, in P. koinopoliteia I 5–6 and II 4–5, P. pali I 3–5 and II 5–6, in P. olegario I 4 and II 5). The following characters are also different from other Brazilian cave species of Pseudochthonius : P. lubueno sp. nov. absent eyes, 30–31 teeth on the fixed chelal finger (in P. gracilimanus due to the presence of 2 small eyes and 23–26 teeth; in P. ricardoi due to 2 eyespots and 43 teeth). Pseudochthonius lubueno sp. nov. also differ from Pseudochthonius of the world: differs from P. arubensis , by the rallum with 6 blades (5 blades in P. lubueno sp. nov.) and the number of chelal fixed and movable finger with 28 teeth (in P. lubueno sp. nov. fixed finger with 34 male / 32 female and movable finger with 29 male / 30 female); differ from P. troglobius by the rallum with 8 blades, the homodentate chelal teeth on the fixed finger, with 65 teeth and the presence of one small coxal spine on coxa III (in P. lubueno sp. nov. rallum with 5 blades, 30 acute teeth and coxal spines on coxa III absent). In the case of ratio trichobothrium ist, ist–est/ist–esb, ( P. lubueno sp. nov. = 1.90), 2.4 in P. arubensis and 1.72 in P. galapagensis Beier, 1977 .

There are also differences in the proportions of some body parts: P. lubueno sp. nov. 1.3 (1.0 female) times longer than carapace and 2.6 (2.8 female) times longer than patella, differs from the P. strinatii 1.3 and 2.0 (2.5 female), and P. ramalho 1.4 (1.2 female) and 2.2 (2.6 female); P. lubueno sp. nov. pedipalp femur 3.0–4.5 times longer than broad, differs from the P. biseriatus (6.4–6.6), P. strinatii (5.3–6.8), P. homodentatus (4.6–4.9); P. lubueno sp. nov. pedipalp chela 5.3 (5.4 female), differs P. biseriatus (7.5–8.0), P. strinatii (6.7– 7.4), P. diamachi (7.7–7.8) and P. ricardoi (6.0); in P. biseriatus femur 1.89 (1.77 female) longer than patella, in P. ricardoi 1.72 longer than patella, differs of the P. lubueno sp. nov. 3.7 (2.25 female) longer than patella.

Description (male and female). Body: coloration of specimens in 70% ethanol generally pale yellow, tergites III–V with a dark median mark ( Fig. 3 ); Male is slightly smaller than female.

Chelicera ( Fig. 4C ). Five setae on hand, with one seta (dt) on the basal position of the fixed finger and one seta (gl) close to the basal seta on the movable finger, with lateral microsetae (vb); All setae acuminate; Fixed finger with 7 (male)/8 (female) teeth proximally reduced in size; Movable finger with 8 (male)/9 (female) teeth proximally reduced in size with subapical isolated tooth (di); Serrula exterior with 12 (male), 13 (female) lamellae; Rallum with 5 blades pectinated ( Fig. 4D ); Dorsal face of cheliceral palm with 4 lyrifissures, 2 situated near setae it and vb, 1 lyrifissure positioned anteriorly on the fixed finger.

Carapace ( Fig. 4A ). Anterior margin slightly serrated on the sides and distinctly serrate with median denticles in the middle; Epistome prominent and dentate; without any traces of eyes; posteriorly constricted; Chaetotaxy 6:4:4:2:2 (18), of which one pair are preocular microseta; 2 lyrifissures anteriorly and 1 posteriorly.

Pedipalp ( Fig. 5 AB). 1.4 (male), 1.2 (female) × longer than carapace and 2.2 (male), 2.6 (female) × longer than patella; movable finger 1.6 (male), 1.9 (female) × longer than hand; fixed finger 1.65 (male), 1.72 (female) × longer than hand. Fixed chelal finger long and strongly sigmoid in its distal half. Fixed finger with 34(male)/32(female) acute teeth, distinctly separated from each other, but paired and in each pair, one tooth is slightly directed retrolaterally and the other prolateral. Movable finger with 29(male)/32(female) flattened and separated teeth. Trichobothria. ib and isb situated close to each other sub–medially in the dorsal region of the chelal hand; eb closer to esb than to ist, forming a straight oblique row at the base of the fixed chelal finger; ist closer to esb than to the est (ratio ist-est/ist-esb = 1.9); et slightly near the tip of the fixed finger, near to the chelal teeth; dx, located near to the end of the fixed finger; t closer to st and situated at the same level as est.

Abdomen. Chaetotaxy of tergites I–XI: male, 3: 3: 4: 3: 5: 4: 4: 3: 4: 4: 3; female, 4: 4: 4: 4:5: 6: 6: 6: 6: 5: 3. Chaetotaxy of sternites III–XI: (male/female) 12: 13: 8: 8: 8: 8: 6: 5: 2, anal cone 0/2 setae.

Genital area ( Fig. 4F, G ): Anterior genital operculum with 9(male)/8(female) marginal and discal setae, genital opening slit-like triangular in male, with 10 marginal setae on each side; posterior operculum with 8 setae in female.

Coxae ( Fig. 4E ): Manducatory process distally acute, with 2 setae; Pedipalpal coxa with 3 setae; Coxa I with 2 setae on anterior margin and coxa II with 4–5 highly dented coxal spines in decreasing size distally, Coxa III with 6 setae and coxa IV with 8 setae; Intercoxal tubercle absent.

Legs ( Fig. 5C, D ): Leg I ( Fig. 5C ): femur 5.9 (male)/7.2 (female) times longer than deep and 1.94 (male)/2.25 (female) longer than patella, patella 3.6 (male)/3.2 (female) times longer than deep, tibia 5.2 (male)/3.8 (female) times longer than deep, tarsus 11 (male)/9.6 (female) times longer than deep, tarsus 1.6 (male)/1 (female) times longer than tibia. Leg IV ( Fig. 5D ): Trochanter 1.1 (male)/1.2 (female) times longer than broad, femur + patella 2.7 (male)/5.8 (female); Tibia 4.8 (male)/3.2 (female) times longer than deep; basitarsus 4.3(male)/3.6 (female) times longer than deep; telotarsus 10.5 (male)/14 (female) times longer than deep.

Measurements and ratios: see Table 1.

Etymology. The specific epithet is a combination in honor of Luciana Bueno dos Reis Fernandes, technician of Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Carlos, an excellent photographer, illustrator, and enthusiast of cave fauna; it is a noun in apposition.

Figures

Figure 3. Pseudochthonius lubueno sp. nov. Paratype female, habitus: (A) dorsal view; (B) ventral view. Scale bar: 0.5 mm. Photo: Luciana Bueno dos R. Fernandes.

Figure 4.Pseudochthonius lubueno sp. nov., male holotype (A-F) and female paratype (G): (A) carapace dorsal view; (B) detail of the anterior margin, with the epistome; (C) left chelicera; (D) rallum; (E) coxal spines of coxae I–II; (F) genital opening; (G) genital opening, paratype. Scale bars: A, C, E, F-G = 0.05 mm, B = 0.2 mm, D = 0.02 mm.

Figure 5. Pseudochthonius lubueno sp. nov., male holotype: (A) left chela, lateral view; (B) left palpal trochanter, femur, and patella; (C) leg I, lateral view; (D) leg IV, lateral view. Scale bars: 0.2 mm.