Plistobunus columnarius, Lian, Wei-Guang, Zhang, Chao & Zhang, Feng, 2011

Lian, Wei-Guang, Zhang, Chao & Zhang, Feng, 2011, Review of the genus Plistobunus Pocock, 1903, with description of a new species from Hainan Island, China (Opiliones, Laniatores, Epedanidae), ZooKeys 112, pp. 39-52 : 43-44

Plistobunus columnarius sp. n. Figs 7-23

Type material.

Holotype male (Opi.11061601), CHINA: Hainan Province, Tunchang County, Xichang Town [N19°26', E 110°02'], June 16, 2009, C. Zhang leg. (MHBU), paratype 1♀(Opi.11061602), same data as holotype.

Diagnosis.

The new species is similar to the type species Plistobunus rapax Pocock, 1903, but can be easily distinguished from the latter by: 1) anterior margin of carapace with a row of six setiferous tubercles on either side; 2) the femur of pedipalpus ventrally with 13 setiferous tubercles in male and seven setiferous tubercles in female; 3) the medial surface of cheliceral proximal segment with a huge protuberance at base.

Etymology.

The specific name is derived from the Latin adjectives “columnaris” meaning columnar, refers to shape of the stylus in male penis.

Description.

Male (holotype) habitus as in Figs 7-8. Coloration: entire body rusty yellow, with somewhat dark brown to blackish brown patches on the dorsum; median area of carapace with blackish brown reticulations; each side of carapace dark brown; lateral ridges of the scute margined with blackish brown; venter concolorous with dorsum; coxae with dark brown reticulations; free sternites with transverse band of blackish brown; chelicerae rusty yellow, with blackish brown reticulate markings above; pedipalpus dark brown, tibia and tarsus paler, tarsus with dark brown reticulations dorsally; legs brown, trochanters yellow, femur, patella and tibia with blackish brown reticulations, metatarsus and tarsus lighter.

Dorsum.

Dorsal scutum trapezoid in shape; widest portion of body at forth scutal area. Carapace with a row of six small setiferous tubercles on each side of front margin. Surface of dorsum almost smooth. Ocularium wide oval, remote from anterior border of scutum, armed with a long erect median spine. Opisthosomal region of scutum with four areas, first area well defined, entire. Second area with two long median spines. Third with a pair of hair-tipped tubercles removed from each other. Fourth with a transverse row of nine tubercles, median tubercle enlarged into a spine. Each lateral margin of the scutum with a longitudinal row of minute hair-tipped granules. Free tergites each with a transverse row of hair-tipped granules spread over its entire width.

Venter.

All coxae and genital operculum granulate. Coxae I–III disto-dorsally with two coarse tubercles on anterior and posterior sides respectively. Coxa IV with a reduced one on medio-prolaterally. Coxa I medio-ventrally and prolaterally with transverse rows of hair-tipped tubercles. Coxae II–III medio-ventrally with a transverse row of same tubercles. Coxa III with prolateral and retrolateral rows of small humps. Coxa IV widened, with hair-tipped granules. Free sternites each with a transverse of hair-tipped granules. Tracheal stigma clearly visible.

Chelicera (Figs 9-12).

Fairly strong. Proximal segment elongated and with numerous hair-tipped tubercles above; the dorsal surface centrally with six hair-tipped tubercles, of which distal one the largest, three medium-sized tubercles posterior to it, and two smaller ones toward the medial side; the ventral surface and the medial surface with rows of eight hair-tipped tubercles respectively, the medial surface with a huge protuberance at base; the ectal surface with a row of seven tubercles. Second segment considerably widened, medially with five enlarged hair-tipped bifid tubercles and ectally with five reduced ones on prodorsal surface, medially with many small hair-tipped granules on ventral surface, the largest one towards the base of fingers. Fingers relatively strong, inner edges toothed as illustrated (Fig. 11): moveable finger with four teeth, the proximal one square, the middle with two crest teeth, the distal one rectangular; fixed finger with five teeth, the proximal two formed one bifid tooth, the middle with one conical tooth, the distal with two lower than the middle one.

Pedipalpus (Figs 13-14)

Coxa dorsally with one proximal and one strong distal bifurcate setiferous tubercles, ventrally with a row of five setiferous tubercles, two enlarged ones additionally at base. Trochanter ventrally with three setiferous tubercles, dorsall y with one. Femur elongate, ventrally with 13 setiferous tubercles, dorsally with nine ones of which the distal two inconspicuous, distally on medial side with two setiferous tubercles of which the distal one tipped and the other one conical. Patella very long, widening abruptly distally, with two setiferous tubercle disto-medially and three setiferous tubercles ectally, dorsally with five inconspicuous granules. Tibia with three medial and five ectal setiferous tubercles, with a row of six hair-tipped granules in the ventral surface. Tarsus with four setiferous tubercles on both sides of ventral surface, with three granules in the ventral surface. Tarsal claw nearly as long as tarsus, strongly curved.

Legs.

Legs I–II slender and legs III–IV strong. Trochanters I–II each with one hair-tipped tubercles arising distally on the dorsal surface, the ventral surface with three hair-tipped tubercles. Trochanters III-IV smooth dorsally, with inconspicuous granules ventrally. Femur I–II ventrally with a row of 10 or 17 setiferous tubercles respectively (Fig. 15). Femur III ventrally with two rows of 12 and 14 setiferous tubercles respectively. Femur IV ventrally with two rows of many granules. The remaining leg-segments unarmed, smooth, with hairs. Tarsi III–IV with bare double claws, without scopulae. Tarsal formula: 8/17/7/8. Distitarsus of the first and second tarsi with two segments.

Penis (Figs 25-31).

slender, its shaft widened distally. The apical structure is divided by lateral incisions into both DP and VP. The VP with complex structures, is separated again by a median cleft, consists of two LPs and the membrane between both sides. The DP simple, distal margin corrugate. G protruding beyond the anterior margin of the dorsal surface. SL somewhat as the shape of tulip ventrally and dorsally, consists of VSL and DSL. The VSL slightly curved toward ventral surface and with a labiate protrusion distally. The DSL petaloid. S smooth, columnar and arising straight from the glans, SL almost entire surrounding the S. BS globular, well developed, immovable and entire sunken into truncus. Setae arranged as follow: 11 VS, four DS, four LS, four GBS.

Female (Figs 16-24).

In general appearance similar to the male but smaller and with abdomen more rounded posteriorly (Fig. 17). Chelicera (Figs 18-20) smaller and with reduced tubercles, the proximal segment shorter than those of the male, the second segment is not so greatly enlarged as in the male, inner edges of finger toothed as illustrated (Fig. 20). The pedipalpus (Figs 21-22) femur with seven reduced setiferous tubercles ventrally and two conspicuous setiferous tubercles dorsally, distally on medial side without any setiferous tubercle; Patella with two setiferous tubercle disto-medially and one setiferous tubercles disto-ectally. Setiferous tubercles of leg I (Fig. 16), as well as leg II–IV inconspicuous. Tarsal formula: 7/17/7/8. Distitarsus of the first and second tarsi with two segments.

Ovipositor (Figs 23-24).

Ventral surface with five setae and dorsal surface with six setae. Tip of each seta pinpoint (Fig. 23).

Measurements.

Male holotype (female paratype): body 3.57 (3.37) long, 2.70 (2.65) wide at the widest portion, scutum 3.21 (2.75) long. Ocularium 0.38 (0.33) long, 0.90 (0.68) wide. Pedipalpus claw 0.90 (0.83) long. Penis 1.55 long. Measurements of left pedipalpus and legs as in Table 1.

Habitat.

Collected by leaf litter sieving in the rubber forest.

Distribution.

China: Hainan (Tunchang County).

Remarks.

A certain similarity in ornamentation of the new species may be noted with that of Plistobunus rapax as figured and described by ( Roewer (1912, 1923, 1938) and Pocock (1903), e. g., the high erect spine on ocularium, fused scutal areas I–II, a pair of spines on the second opisthosomal area, a spine on the fourth opisthosomal area of the dorsal scutum, the greatly elongate pedipalpus and almost identical chelicera. The style of the ornament of the new species is typical of Plistobunus . Based on above we believe it should be a new species.

Martens (1988) suggested that "an intensive search, not only for diverse morphological structures in laniatorid penes, but even more for the function of their movable parts under hemolymph pressure will reveal a wealth of structures up to now largely undiscovered". Many families (e. g., Assamiidae Sørensen, 1884; Biantidae Thorell, 1889; Fissiphalliidae Martens, 1988; Oncopodidae Thorell, 1876; Phalangodidae and Podoctidae Roewer, 1912) were studied in genital morphology and function. At the meantime, some laniatorid structure cannot be homologized completely. Epedanidae is restricted in Asia, among of these known species, Suzuki porvided drawings of genital morphology, however, he failed to give the expanded the structures of the penis.

In this paper, we tentatively explain the movement of the penis in the new species briefly. The S is mainly exposed by the movement of VSL and DSL in the opposite direction, DSL tends to move dorsally wider than that of VSL. DSL and VSL like the petal, S is similar to the stamen. The expansion of G resembles the blooming flower (Fig. 31).