Charinus kakum, Harms, Danilo, 2018

Harms, Danilo, 2018, A new species of Charinus (Amblypygi: Charinidae) from Ghana, with notes on West African whip spiders, Evolutionary Systematics 2 (1), pp. 45-53 : 45

Charinus kakum sp. n. (Figs 1, 2, 3, 4, 5)

Type material.

Female holotype: GHANA, Central Province, Kakum National Park, Track to Treehouse (5°21 ’21.23” N; 1°22 ’55.87” N), under flat rock near forest floor, 13.XII. 2017, coll. D. Harms and B.K. Williams (ZMH-A0000893).

Diagnosis.

Charinus kakum sp. n. differs from the cave-inhabiting species C. milloti Fage, 1939 and C. fagei Weygoldt, 1972 in low number of tibial segments on leg IV (5 in C. millotei and C. fagei vs. 3 in C. kakum ), trichobothria patterns of leg IV (compare with Weygoldt 1972, 2000a), small body size (prosoma length 2.6 in C. kakum ), and shorter legs; from the island species C. africanus Hansen 1921 through the female genital operculum which has a steep ventral flexure at about two third of its length in C. africanus ( Weygoldt 1972; Miranda et al. 2016b) but is uniform in C. kakum , and body size (ca. 8.0-8.5 mm in C. africanus and 5.8 in C. kakum ; Hansen 1921).

Description.

Carapace: flattened and wider than long (Figs 3A, C), uniformly brown except for the margins that are pale. Ratio length/width approximately ¾. Anterior margin rounded and with six spines situated anterior to the ME, individual spines projecting upwards. ME well developed, projecting forwards and situated on a common dark tubercle. LE well developed and on a common tubercle, projecting sideward. Fovea well developed and rounded, followed by a triangular depression at the posterior margin of the carapace. Three additional depressions in lateral position: i) smallest situated posterior to the LE; ii) a second larger depression in mediolateral position; and iii) a posterior-lateral position. Carina runs from the corners of the anterior margin and extends from the coxae of legs I to the corners of the posterior margin. Small granules and punctuations present, denser at the anterior region and pars cephalica. Sternum: tri-segmented but individual segments weakly sclerotized and rounded (Fig. 3B, D), pale except for the reddish-brown sternites. Tritosternum projected anteriorly and reaching far into the coxae of the pedipalps, elongate and cone-shaped, with one apical pair of spines, one medial pair, and ca. 6 spinelets at the base, distal margins serrate, base more or less triangular. Tetrasternum (second segment) rounded and hard to discern, with a pair of spinelets. Pentasternum (third segment) reduced and hard to discern, with a pair of setae (or small spinelets). Two additional setae between coxae of leg IV. The segments separated from each other by ca. 1.5 times the diameter of the tetrasternum. Opisthosoma: ovate and light brown, except for the tergites that are brown (Figs 2 C; 3A, B). Tergites with punctuations, in particular the distal positions. Tergites distally also with a small longitudinal row of up to 6 tiny setae. Chelicera: Cheliceral furrow with 4 teeth of the basal segment (Figs 4D, E; 5B). Proximal tooth largest, size range: IV>I>II>III. Distal tooth bifid and distal cusp larger than proximal cusp. Claw with 5 basal teeth, the 3 proximal teeth on a common base; some fine hairs at the retrolateral margin, condyle strongly sclerotized and reddish-brown, fang brown. Basal segment dorsally with four setae: first one situated distally near fang condyle, two medio-distal, and one in medial position. Both sides of basal segment with a longitudinal band of five or six fine setae. Ventral side of basal segment setose and reddish. Pedipalp: Trochanter (Fig. 4 A–C): Ventral apophysis sharply pointed and with a series of 14 strong spines (Fig. 4C); distal three largest, proximally decreasing in size; prolateral side with one spine and 3 spinelets (Fig. 4A). Femur: with three rows of spines, prolateral row with 5 setiferous tubercles, median row with large 3 spines (size ranges distal to proximal II>III>I), and retrolateral row with 4 spines (size range distal to proximal II>III>I>IV). Spines of retrolateral row largest. Size distal to proximal II>III>I>IV. Some setae present distally in pro- and retrolateral position (Fig. 4A, B; 5A). Tibia: with typical charinid spine armature ( Weygoldt 2000a). Retrolateral side with 3 spines and one distal setiferous tubercle; distal spine largest and and spines proximally decreasing in length (III>II>I), distal setiferous tubercle near base of basitarsus in front of largest spine; Prolateral side with 2 spines and one proximal spinelet, distal spine largest. Dorsal side of tibia adorned with setae that distally decrease in length. Basitarsus: broadly flattened and each side with 2 spines, distal ones largest but proximal spine in retrolateral position much smaller (Fig. 4A). Retrolateral surface with several spinelets, prolateral surface smooth and with a median row of three trichobothria-like setae plus three additional setae more retrolaterally. Distitarsus: with 2 small spines above the cleaning organ, distal one about twice the size of proximal spine. Dorsal side setose, ventral side with ca. 10 long setae which are distally serrate. Cleaning organ occupies about 1/2 of the article length. Claw: long and with sharp curved tip, ca. 2/3 the length of distitarsus, divided from distitarsus and not fused. Legs: All moderately setose. Femur lengths: I>III>II>IV. Leg I: tibia with 24 articles and tarsus with 41 articles. Leg IV: Barsitibia with 3 pseudoarticles and distitarsus undivided. Trichobothria pattern: pseudosegment one: 1, two: 1, three: 11 (Fig. 5D). All claws smooth and not serrate. All walking legs with pulvilli that are slightly smaller than the claws. Genitalia: Genital operculum rounded but distolateral margins concave (Fig. 2B). Sparsely setose in the proximal section but distal margins with ca. 22 setae. Genital opening rounded and slightly concave in distal view. Ventral sac covers visible and medially fused. Gonopods longer than wide and with rounded openings (Fig. 5C), separated by ca. the diameter of their base; otherwise indistinct and comparable to other species of the genus (e.g. compare Vasconcelos and Ferreira 2017).

Colour.

Body chestnut brown (dark brown in the life animal), abdomen yellowish except for the tergites. Chelicerae and distal sections of the pedipalp reddish (Figs 2A; 3A, B).

Measurements.

Total length 5.8: Carapace: Length: 2.6; Width: 1.9; Opisthosoma Length: 3.3; Opisthosoma Width: 2.25. Left Pedipalp: Femur: 1.35; Tibia: 1.66; Basitarsus: 0.57; Distitarsus: 0.58; Claw 0.43. Chelicera (basal segment): Length: 0.85. Width: 0.53.

Etymology.

The specific epithet refers to the type locality, Kakum National Park in Ghana.

CO1 gene sequence. GenBank Submssion No. MH107031

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Distribution.

Only known from the type locality by a single female individual. The wider distribution remains unknown and unfortunately no other specimens could be collected, despite targeted searches in the vicinity of the type locality.

Habitat.

The species was collected in closed primary rainforest in Kakum National Park, Ghana (Fig. 1). It was found in a small rocky outcrop close to a dry creek-bed under a rock which was positioned directly on top soil. Other arachnids that were seen at this outcrop included Ricinoides sp. ( Ricinulei ) and schizomids ( Uropygi : Schizomida ). No other specimens could be found under adjacent rocks or tree bark. Kakum National Park comprises moist evergreen (where the holotype was collected) and swamp or riverine forests. Average annual rainfall is ca. 1380 mm and the elevation range is 135-250 meters.

Notes on biology.

The collected female was brooding and carried a total of seven eggs in a brood sac. These eggs were large, ca. 1.25 mm in diameter (Fig. 2D). Considering the low number of eggs and their large size, the reproductive potential of this species is considered to be low. Nothing else is known about the biology and distribution of this species. So far, it is the smallest whip spider in western Africa and may have a preference for rocky boulders in densely vegetated areas, under which it retreats.