Nannarrup oyamensis Tsukamoto, 2022

Tsukamoto, Sho, Shimano, Satoshi & Eguchi, Katsuyuki, 2022, Two new species of the dwarf centipede genus Nannarrup Foddai, Bonato, Pereira & Minelli, 2003 (Chilopoda, Geophilomorpha, Mecistocephalidae) from Japan, ZooKeys 1115, pp. 117-150 : 117

Nannarrup oyamensis Tsukamoto sp. nov.

New Japanese name: Amefuri-himejimukade Figs 12 , 13 , 14 , 15 , 16 , 17

Type material.

Holotype 1 adult male, Hinata, Isehara-shi, Kanagawa prefecture, Japan (35°26.07'N, 139°14.75'E), 17 February 2021, coll. Sho Tsukamoto (labeled as TS20210217-04), deposited at the Collection of Myriapoda, Department of Zoology, NSMT. Paratype 1 subadult male, Hinata, Isehara-shi, Kanagawa prefecture, Japan (35°26.07'N, 139°14.75'E), 25 July 2021, coll. Sho Tsukamoto (labeled as TS20210725-02), deposited at MNHAH.

Etymology.

The species name is derived from the name of Japanese mountain, namely Mt. Oyama. The word was further Latinized by adding the Latin masculine adjective suffix - ensis, to form Nannarrup oyamensis oyamensis . The last “a” of Oyama and the first “e” of -ensis are merged into “e.” Examined specimens were collected from Mt. Oyama, an object of the mountain worship.

Diagnosis.

Clypeus without smooth or weakly areolate areas along the posterior part of the paraclypeal sutures; forcipular trochantroprefemur with a large denticle (longer than wide); tarsungulum with a well-pigmented denticle; metasternite of ultimate leg-bearing segment wider than long.

Description.

General features: Body 8.6 mm long (holotype), gradually attenuate posterior, almost uniformly very pale yellow, with head and forcipular segment pale ocher.

Cephalic capsule (Fig. 12A, B ): Cephalic plate ca 1.5 × as long as wide, lateral margins more distinctly converging anteriorly than posteriorly, posterior margin straight; scutes approximately isometric and up to ca 15 μm wide; transverse suture absent; setae up to ca 50 μm long. Clypeus ca 1.5 × as wide as long, with lateral margins complete, almost uniformly areolate, with scutes ca 10 μm wide, a pair of clypeal areas absent; 13 setae in holotype, 1+1 postantennal, 1+1 median, 5+4 prelabral; clypeal ratio ca 1: 7; clypeal plagulae without additional smooth area along posterior part of paraclypeal sutures; 17 pore-like organs on entire part of clypeus. Anterior and distolateral parts of pleurites areolate, without setae. Side-pieces of labrum medially in contact, only incompletely divided into anterior and posterior alae by weak chitinous line, without longitudinal stripes on posterior alae; with slightly visible short fringe on posterior margin of side-pieces; mid-piece as long as wide, converging anteriorly and posteriorly.

Antenna (Fig. 13A-D ): Antenna with 14 articles, when stretched, ca 2.3 × as long as head length. Intermediate articles slightly longer than wide. Article XIV ca 2.0 × as long as wide, ca 1.9 × as long as article XIII, and 1.9-2.1 × as long as intermediate articles. Setae on articles VIII-XVI denser than articles I-VII. Setae gradually shorter from article VIII to XIV, up to 50 μm long on article I, up to 33 µm long on article VIII and <18 μm long on article XIV. Article XIV with two types of sensilla, apical sensilla (arrows in Fig. 13C, D ) ca 5 μm long, with wide flat ring at mid-length; club-like sensilla (arrowheads in Fig. 13C, D ) ca 10 μm long, clustered in the distal parts of the internal and external sides of the article. Three longitudinal rows consisted of ca 9 proprioceptive spine-like sensilla at bases of antennal articles II-V, VII-IX, approximately dorsal, ventro-internal and ventro-external; rows reduced to 1-3 spines on antennal articles I and VI, and 0-1 spine on antennal articles X-XIV. A few pointed sensilla, up to 2.5 μm long, on both dorso-external and ventro-internal position, close to distal margin of articles II, V, IX and XIII.

Mandible (Fig. 14A ). At least four pectinate lamellae, with elongated teeth. Each tooth ca 2 × as long as wide.

First maxillae (Fig. 14B ): Coxosternite medially divided but slightly, without setae, faintly areolate. Coxal projections well developed and hyaline distally, provided with 1+1 setae and 3+4 small sensilla. Telopodite uni-articulated and hyaline distally, with one (two) seta(e). No lobes on either coxosternite or telopodites.

Second maxillae (Fig. 14B ): Coxosternite medially undivided, without suture, with 2+3 setae along the anterior margin, with 4+4 setae located behind anterior margin, with anterior margin slightly concave, with metameric pores on posterior part. Telopodites tri-articulate overreaching medial projections and telopodites of first maxillae. Claw of telopodite virtually absent, represented by short spine only.

Forcipular segment (Fig. 15A-D ): Tergite trapezoidal, ca 1.9 × as wide as long, with lateral margins converging anteriorly, approximately as wide as cephalic plate and ca 0.7 × as wide as following tergite, 1+1 setae of similar length arranged in an anterior row, and 3+3 setae of similar length arranged in a posterior row, one pair of longitudinal rows of three tiny setae located between middle and distal setae in posterior row. Mid-longitudinal sulcus of tergite not visible. Exposed part of coxosternite ca 1.3 × as wide as long; anterior margin with shallow medial concavity and with one pair of denticles; coxopleural sutures complete in entirely ventrum, sinuous and diverging anteriorly; chitin-lines absent. Basal distance between forcipules ca 0.1 × of maximum width of coxosternite. Trochanteroprefemur ca 1.3 × as long as wide; with a well-developed and strong pigmented denticle at distal internal margin, ca 1.3 × as long as wide. Intermediate articles distinct, tubercle on tibia not visible. Tarsungulum with basal denticle well-pigmented; both external and internal margins uniformly curved, except for moderate mesal basal bulge; ungulum not distinctly flattened. Elongated poison calyx (circle in Fig. 15D ), ca 6 × as long as wide, lodged inside intermediate forcipular articles.

Leg-bearing segments (Fig. 16A-D ): Forty-one pairs of legs present. Metatergite 1 slightly wider than subsequent one, with two paramedian sulci visible on tergites of anterior half of body, without pretergite. No paratergites. Walking legs shorter than width of trunk; legs of first pair much smaller than following ones; claws simple, uniformly bent, with two accessory spines; anterior spine reaching at most 10% of length of claw; posterior spine shorter than anterior spine. Metasternites slightly longer than wide. Sternal sulcus visible on a few anterior sternites, represented by very shallow mid-longitudinal thickening, anterior not furcate. No ventral glandular pores on each metasternite.

Ultimate leg-bearing segment (Fig. 17A-D ): Pretergite not accompanied by pleurites but incomplete traces of sutures present at both sides. Metatergite subtrapezoidal, almost as wide as long, lateral margins convex and converging posteriorly; posterior margin slightly curved. Coxopleuron ca 1.2 × as long as metasternite; coxal organs of each coxopleuron opening through five or six independent pores, placed ventrally. Metasternite subtriangular, ca 1.6 as wide as long, anteriorly ca 3.5 × as wide as posteriorly; lateral margins slightly convex and converging backward; setae almost arranged symmetrically, dense on posterior margin. Telopodite ca 11 × as long as wide, ca 1.9 × as long and ca 1.3 × as wide as penultimate telopodite, with 6 articles; tarsus 2 ca 2.7 × as long as wide and ca 1.5 × as long as tarsus 1; setae arranged uniformly, <50 μm long. Pretarsus represented by spines, up to 5 µm.

Male postpedal segments (Fig. 17A, B ): Two gonopods, very widely separated from one another, conical in outline, uni-articulated without any sutures, covered with setae. Anal pore present.

Female postpedal segments unknown (female unknown).

Distribution.

Only known from Mt. Oyama, located in Isehara-shi, Kanagawa prefecture.

Remarks.

Nannarrup oyamensis sp. nov. is distinguishable from the two congeners by the absence of smooth or weakly areolate areas along the posterior part of the paraclypeal sutures. Specifically, N. oyamensis sp. nov. can be clearly distinguished from N. hoffmani by the presence of a well-developed denticle on the trochanteroprefemur (width: length = 1:1.3) and the absence of smooth or weakly areolate areas along the posterior part of the paraclypeal sutures. Furthermore, N. oyamensis sp. nov. can be distinguished from N. innuptus sp. nov. by the absence of a pair of smooth or weakly areolate areas along the posterior part of the paraclypeal sutures (see Table 3 for a comparison of characteristics).

Figures

Figure 12. Nannarrup oyamensis sp. nov., holotype (TS 20210217 - 04) A cephalic plate, dorsal B clypeus and clypeal pleurite, ventral. Scale bars: 0.1 mm.

Figure 13. Nannarrup oyamensis sp. nov., holotype (TS 20210217 - 04) A right antenna, dorsal B right antenna, ventral C antennal article XIV, dorsal D antennal article XIV, ventral. Arrows indicate apical sensillum; arrowheads indicate club-like sensillum. Scale bars: 0.1 mm (A, B); 0.05 mm (C, D).

Figure 14. Nannarrup oyamensis sp. nov., holotype (TS 20210217 - 04) A right mandible, ventral B maxillae complex, ventral. Scale bars: 0.05 mm.

Figure 15. Nannarrup oyamensis sp. nov., holotype (TS 20210217 - 04) A forcipular segment, dorsal B forcipular segment, ventral C denticles on right forcipule, dorsal D left poison calyx, dorsal. Circle indicates poison calyx. Scale bars: 0.1 mm (A, B); 0.05 mm (C, D).

Figure 16. Nannarrup oyamensis sp. nov., holotype (TS 20210217 - 04) A pretarsus of left leg 40, dorsal B pretarsus of left leg 40, ventral C tergite of leg-bearing segment 40, dorsal D sternite of leg-bearing segment 40, ventral. Scale bars: 0.05 mm (A, B); 0.1 mm (C, D).

Figure 17. Nannarrup oyamensis sp. nov. A, B holotype (TS 20210217 - 04) C, D paratype (TS 20210725 - 02). A ultimate leg-bearing segment and male postpedal segment, dorsal B ultimate leg-bearing segment and male postpedal segment, ventral C right ultimate leg, dorsal D right ultimate leg, ventral. Scale bars: 0.1 mm.