Mecistocephalus smithii Pocock, 1895

Pan, Yang-Yang, Fan, Jia-Bo, You, Chun-Xue & Jiang, Chao, 2024, Identification of two new species of Mecistocephalus (Chilopoda, Geophilomorpha, Mecistocephalidae) from southern China and the re-description of Mecistocephalus smithii Pocock, 1895, ZooKeys 1218, pp. 1-23 : 1-23

Mecistocephalus smithii Pocock, 1895

Figs 7 , 8

Mecistocephalus smithii Pocock, 1895: 351.

Material examined.

• 2 ♂♂, 5 ♀♀; ( CMMI 20191014012 , - 032, 20191014034-20191014036); China, Guangdong Province, Guangzhou, Maofengshan Forest Park; 23.2983 ° N, 113.4644 ° E; 330 m a. s. l.; 14 Oct. 2019; coll. Chao Jiang . • 2 ♀♀; ( CMMI 20201217111 , 20201217112); Guangdong Province, Heyuan, Xinfengjiang Reservoir ; 23.7703 ° N, 114.6300 ° E; 180 m a. s. l.; 17 Dec. 2020; coll. Zhidong Wang . • 1 ♀; ( CMMI 20191031042 ); Zhejiang Province, Zhoushan, Changgangshan Forest Park; 30.0355 ° N, 122.1201 ° E; 130 m a. s. l.; 31 Oct. 2019; coll. Chao Jiang . • 2 ♂♂, 1 ♀; ( CMMI 20201108123 , - 124, - 126); Jiangsu Province, Nanjing, Fuguishan Forest Park; 32.1006 ° N, 118.586 ° E; 130 m a. s. l.; 8 Nov. 2020; coll. Zhidong Wang .

Diagnosis.

A Mecistocephalus species with 59 leg pairs. Head length-to-width ratio ~ 1.7, each side of clypeus with ~ 20–22 setae, clypeal ratio (areolate part / non-areolate part) of ~ 1, plagulae with sensilla, cephalic pleurite without setae, forcipular coxosternite only with a part of short cerrus. Sternal sulcus with short branches.

Re-description.

Body length 74–88 mm (limited to the above samples); posterior part slightly slender. Head and forcipular segment dark red in color; remainder yellow.

Cephalic plate (Fig. 7 A ): sub-rectangular, length-to-width ratio 1.7–2.1; lateral margins slightly convergent backward, the maximum width 2.65 mm; transverse suture protruded to the back edge of the cephalic plate, vertex pointed; suture line on the back side of the cephalic plate with four to six setae; dorsal cephalic plate with scattered puncta. Antennae 5.3 × as long as the head width. Apical sensilla ~ 10 μm long.

Clypeus (Fig. 7 B ): clypeal ratio (areolate part / non-areolate part) ~ 1; each side with 20–22 setae; the transverse suture of clypeal plagulae slightly protrude from the front cephalic plate; plagulae with groups of small sensilla localized to anterolateral corners.

Labrum (Fig. 7 B ): anterior ala medial marginal ~ 1 / 3 of posterior ala; middle piece protrudes forward into a vertex over side pieces; posterior line of side pieces curve, convex with respect to straight anterior margin; the hair-like fringes and projections on the labral side pieces absent, the comma-shaped sclerite lateral to the labral side pieces present.

Cephalic pleurite (Fig. 7 C ): spiculum present; cephalic pleurite without setae.

Mandible (Fig. 7 D ): approximately seven to eleven well developed lamellae; first lamella with ~ 5 teeth; average intermediate lamella with ~ 22 teeth; basal teeth small and protruding.

First maxillae (Fig. 7 E ): antero-external corners of coxosternite protruding and short; coxosternite divided by mid-longitudinal sulcus; coxal projection 1–1.2 × as wide as long, 17 setae on medial margin and clavate lappet present; telopodites 2.5–3.4 × as long as wide, clavate lappet present.

Second maxillae (Fig. 7 E ): one sclerotic ridge on the middle of coxosternite with ~ 8 setigerous insulae; telopodite article I 3.33–4.5 × as long as wide, the ventral and dorsal part of interior telopodites both with four vertical setae; anterior article II with nine surrounding setae; article III 2.5–3 × as long as wide, distal end densely setose, pretarsus present.

Forcipular segment (Fig. 7 F – H ): exposed part of coxosternite width-to-length radio 0.8–0.85; cerrus composed of a pair of setae on each side. Forcipular Trochanteroprefemur length-to-width radio of 1.13–1.35, two teeth present; both femur and tibia with one tooth and the former smaller than the latter; tarsungulum with one dark brown and small basal tooth; poison calyx reaching the distal part of trochanteroprefemur.

Leg-bearing segments (Fig. 8 A, B ): 59 leg-bearing segments, a few sternite with sternal sulcus, almost all posterior sternite with setae; sternal sulcus of anterior segments furcate, and with short branches; the first pair of legs much smaller than the others, only one claw at the front.

Ultimate leg-bearing segment (Fig. 8 C, F ): posterior line of metasternite protruding no more than intermediate sternite, sandwiched between two coxopleura; each of coxopleura covered with dense pore-fields except for the ends; ultimate leg-bearing with short setae, claw absent; setae distributed in various parts of the last leg-bearing segment.

Postpedal segments (Fig. 8 C, E, F ): gonopods of both males and females tapered and biarticulated.

Remarks.

To date, within Asia, only two species of the genus Mecistocephalus possess 59 leg-bearing segments: M. diversisternus Silvestri, 1919 and M. smithii Pocock, 1895 . It is noteworthy that some researchers have previously raised concerns regarding the accuracy of M. smithii records in Japan and Taiwan, suggesting that they may represent misidentification of M. diversisternus ( Uliana et al. 2007) . Mecistocephalus smithii was originally described from “ Da-laen-Saen 30 miles S. W. of Ningpo ” and “ Wo Lee Lake, 25 miles S. of Ningpo ” in the Chinese mainland. The locality “ Da-laen-Saen 30 miles S. W. of Ningpo ” is very likely “ Dalei Shan ” near (45 km SW) Ningbo, Zhejiang ( Schawaller and Aston 2017), while the locality of “ Wo Lee Lake, 25 miles S. of Ningpo ” does not match any present geographical name in Ningbo after a survey among local residents. The original account was too brief, and the true identity of M. smithii remained unclear ( Uliana et al. 2007).

To address this problem, we collected and examined new specimens near the type locality, as well as in other provinces. Therefore, we can confidently state that M. smithii is a distinct species to M. diversisternus and that it is present in China. The distinguishing features of M. diversisternus include a limited number of clypeal setae, typically less than ten, and a sternal sulcus that lacks bifurcation. In contrast, M. smithii has abundant setae on each side of the clypeus ranging from 20 to 22 and a bifurcate sternal sulcus with short branches.

Distribution.

China (Zhejiang, Guangdong).

Figures

Figure 7. Mecistocephalus smithii Pocock, 1895 (spm. CMMI 20191014031) A clypeus and cephalic pleurite, ventral view B anterior part of head, ventral view (maxillae removed) C cephalic plate, ventral view (maxillae removed) D mandible E maxillae, ventral view F forcipular segment, ventral view G forcipular segment, dorsal view H a part of right forcipule, ventral view. Part of areolation not drawn. Scale bars: 20 μm (D), 100 μm (H); 1 mm (A-C, E-G).

Figure 8. Mecistocephalus smithii Pocock, 1895 (spm. CMMI 20191014031) A sternite of leg-bearing segment VI, ventral view B tergite of leg-bearing segments VI – VIII, dorsal view C ultimate leg-bearing segment, ventral view D ultimate leg-bearing segment, ventral view (spm. CMMI 20191014012) E ultimate leg-bearing segment and left leg, ventral view F ultimate leg-bearing segment, dorsal view. Scale bars: 1 mm.