Dicellophilus praetermissus, Tsukamoto & Eguchi, 2024

Tsukamoto, Sho & Eguchi, Katsuyuki, 2024, Integrative taxonomy of Dicellophilus Cook, 1896 (Chilopoda, Geophilomorpha, Mecistocephalidae) in Japan, with a description of a new species, Zoosystematics and Evolution 100 (3), pp. 821-840 : 821-840

Dicellophilus praetermissus sp. nov.

Figs 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 New Japanese name: Date-hirozujimukade

DI.

Dicellophilus sp. 0000-0003 - 3020 - 8454 _ 0069

Type material.

Holotype. 1 adult male, Baba , Akiu-machi , Taihaku-ku , Sendai-shi, Miyagi Pref., Japan (38 ° 16.33 ' N, 140 ° 32.69 ' E), 7 October 2020, coll. Sho Tsukamoto (labeled as TS 20201007-02 ), deposited at the Collection of Myriapoda, Department of Zoology, NSMT .

Paratype. 1 adult male, Baba , Akiu-machi , Taihaku-ku , Sendai-shi, Miyagi Pref., Japan (38 ° 16.33 ' N, 140 ° 32.69 ' E), 7 October 2020, coll. Sho Tsukamoto (labeled as TS 20201007-03 ) , 1 adult female, Baba , Akiu-machi , Taihaku-ku , Sendai-shi, Miyagi Pref., Japan (38 ° 16.33 ' N, 140 ° 32.69 ' E), 7 October 2020, coll. Sho Tsukamoto (labeled as TS 20201007-04 ) , 1 adult male, Baba , Akiu-machi , Taihaku-ku , Sendai-shi, Miyagi Pref., Japan (38 ° 16.33 ' N, 140 ° 32.69 ' E), 7 October 2020, coll. Sho Tsukamoto (labeled as TS 20201007-05 ), deposited at MNHAH .

Etymology.

The species name is a masculine adjective derived from “ overlooked ” in Latin. Since the description by Kishida (1928) of D. pulcher (as Mecistocephalus pulcher ), this new species has been overlooked for 90 years, despite documentation of its distribution as Dicellophilus in the Sendai-shi, Miyagi Pref. ( Takakuwa 1940).

Diagnosis.

Trunk segments without dark patches; head 1.4 times as long as wide; lateral margin of cephalic plate abruptly converged posteriorly; clypeus with densely scattered setae; palaclypeal suture evidently converging posteriorly; both ends of transverse suture uniformly rounded; mandible with 6 lamellae; forcipular trochanteroprefemur longer than wide, with one small distal denticle; forcipular tarsungulum with evident and variably spaced notches; metatergite subtrapezoidal; metasternite trapezoidal, wide rather than long; forty-one pairs of legs.

Description.

General features (Fig. 6 ): Body about 50 mm long (holotype ca 52 mm), gradually attenuated posteriorly, almost uniformly pale yellow, with head and forcipular segment ocher.

Cephalic capsule (Fig. 7 A, B ): Cephalic plate ca 1.3–1.4 × as long as wide; lateral margins markedly convex; posterior margin straight; areolate part visible only at anterior margin; scutes approximately isometric and up to 20 μm wide in 50 mm long specimen; both ends of transverse suture uniformly rounded or slightly convex forward; setae up to ca 300 μm long. Clypeus ca 2.3–2.5 × as wide as long, with lateral margins complete, anterior part areolate, with scutes ca 30 μm wide in 50 mm long specimen, clypeal areas absent; clypeus with about 200 setae on most part except lateral and posterior margins; clypeal plagulae undivided by mid-longitudinal areolate stripe. Anterior and distolateral parts of pleurites areolate, without setae, non-areolate part extending forwards distinctly beyond labrum. Side-pieces of labrum not in contact, anterior margin not concave posteriorly but horizontally, divided into anterior and posterior alae by chitinous line, with longitudinal stripes on posterior alae, with medial tooth, and short fringe on posterior margin of side-pieces; mid-piece ca 6.2 times as long as wide, lateral margin concaved.

Antenna (Fig. 8 A – H ): Antenna with 14 articles, when stretched, ca 2.7–3.2 × as long as head length. Intermediate articles longer than wide. Distal part of article areolate, remaining surface not areolate in article I – XIII. Article XIV ca 2.1–2.5 × as long as wide, ca 1.1–1.5 × as long as article XIII. Setae on articles VIII – XVI denser than articles I – VII. Setae gradually shorter from article VIII to XIV, up to ca 290 μm long on article I, up to ca 270 μm long on article VIII and <75 μm long on article XIV. Article XIV with two types of sensilla; apical sensilla (arrows in Fig. 8 G, H ) ca 25 μm long, with wide flat ring at mid-length; club-like (arrowheads in Fig. 8 G, H ) sensilla ca 15 μm long, clustered in distal part of internal and external sides of article. Rows of spine-like basal sensilla (the ‘ sensilla microtrichoidea’ of Ernst 1983, 1997, 2000) absent on antennal article VI and X. A few pointed sensilla, up to 7.5 μm long, on both dorso-external and ventro-internal position, close to distal margin of articles II, V, IX and XIII.

Mandible (Fig. 9 A ): Five – six pectinate lamellae present; first lamellae with at least 4 elongated teeth. Anterior surface hairy.

First maxillae (Fig. 9 B ): Coxosternite medially divided but slightly, without setae, without projection on antero-external corners, non-areolate. Coxal projections well developed, with ca 20 setae along internal margin, distal lobe subtriangular. Telopodite uni-articulated and hyaline distally, with 5–6 setae. No lobes on either coxosternite or telopodites.

Second maxillae (Fig. 9 B ): Coxosternite medially undivided, without suture but areolated on isthmus, with 4 + 4 setae along anterior margin, with about 25 setae on isthmus, with about 15 setae on lateral margin and posterior corners, anterior margin concave, with metameric pores on posterior part. Telopodites tri-articulate, reaching medial projections and telopodites of first maxillae. Claw of telopodite present.

Forcipular segment (Fig. 10 A – E ): Tergite trapezoidal, ca 1.3–1.4 × as wide as long, with lateral margins converging anteriorly, areolation mainly along two marginal lateral and anterior bands and two paramedian posterior areas, gradually fading into central non-areolate surface; ca 0.5–0.6 × as wide as cephalic plate and ca 0.4–0.5 × as wide as tergite 1; 3 + 2 setae of similar length arranged in an anterior row, and ca 20 setae of similar length arranged symmetrically in a posterior row. Mid-longitudinal sulcus of tergite not visible. Pleurite 1.8–1.9 × as long as the tergite; dorsal ridge sclerotized; anterior tip (scapular point) well behind anterior margin of coxosternite, and only slightly projecting. Cerrus composed of a group of 10–20 setae on each side of anterodorsal surface of coxosternite, but no paramedian rows of setae. Exposed part of coxosternite ca 1.2 × as wide as long; anterior margin with shallow medial concavity and with one pair of denticles; coxopleural sutures complete in entire ventrum, sinuous and diverging anteriorly; chitin-lines absent; condylar processes of forcipular coxosternite well developed. Trochanteroprefemur ca 1.3–1.4 × as long as wide; with a pigmented tubercle at distal internal margin. Intermediate articles distinct, with a tubercle on femur and tibia. Tarsungulum with well-pigmented basal tubercle on dorsal surface; both external and internal margins uniformly curved, except for moderate mesal basal bulge; ungulum not distinctly flattened; internal margin of ungulum evidently crenulated, with variably spaced notches. Elongated poison calyx lodged inside intermediate forcipular articles.

Leg-bearing segments (Fig. 11 A – 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, with pretergite. No paratergites. Legs of first pair much smaller than following ones; claws simple, uniformly bent, with 2 accessory spines; posterior spine shorter than anterior spine; with a subsidiary spine near posterior spine (arrow in Fig. 11 D ). Metasternites slightly longer than wide. Sternal sulcus evident on segment II, but fading towards posterior segments, anteriorly not furcate. No ventral glandular pores on each metasternite.

Ultimate leg-bearing segment (Figs 12 A – D , 13 A, B ): Pretergite accompanied by pleurites. Metatergite subtrapezoidal, ca 1.2–1.5 × as long as wide; lateral margins converging posteriorly. Coxopleuron ca 1.8–2.3 × as long as metasternite; coxal organs of each coxopleuron opening through ca 70 independent pores, placed ventrally; distinctly larger pore (macropore) near center of the ventral side. Metasternite trapezoidal, ca 1.1–1.5 × as wide as long, anteriorly ca 3.0–3.6 × as wide as posteriorly; lateral margins converging backward straightly; setae almost arranged symmetrically, dense on posterior margin. In male holotype ( TS 20201004-02 ), telopodite ca 11.5 × as long as wide, ca 1.6 × as long, and ca 1.3 × as wide as penultimate telopodite, with six articles; tarsus 2 ca 3.3 × as long as wide and ca 1.1 × as long as tarsus 1; setae arranged uniformly, <200 μm long; pretarsus without claw. In female paratype ( TS 20201004-04 ), telopodite ca 13.5 × as long as wide, ca 1.8 × as long, and ca 1.3 × as wide as penultimate telopodite, with six articles; tarsus 2 ca 5.2 × as long as wide and ca 1.3 × as long as tarsus 1; setae arranged uniformly, <300 μm long; pretarsus without claw.

Male postpedal segments (Fig. 12 A, B ): Two gonopods, very widely separated from one another, conical in outline, bi-articulated with sutures, covered with setae. Anal pore present.

Female postpedal segments (Fig. 12 C, D ): Two gonopods basally touching, subtriangular, bi-articulated with sutures, covered with setae. Anal pore present.

Distribution.

Only known from the type locality.

Remarks.

Dicellophilus praetermissus sp. nov. most closely resembles D. pulcher but is distinguishable by the following combination of characteristics: both ends of transverse suture not evidently convex forward; the longer than wide trochanteroprefemur; the wide rather than long metasternite (Table 3 ).

The record of D. latifrons Takakuwa, 1934 (= D. pulcher ) from Sendai, Miyagi Pref. ( Takakuwa 1940) requires confirmation of its identification.

Figures

Figure 6. Habitus of Dicellophilus praetermissus sp. nov., paratype (TS 20201007-05). Photo by Joe Kutsukake.

Figure 7. Dicellophilus praetermissus sp. nov., holotype (TS 20201007-02) A cephalic plate, dorsal B clypeus, and clypeal pleurite, ventral. Scale bars: 0.5 mm.

Figure 8. Dicellophilus praetermissus sp. nov. A – F. Holotype (TS 20201007-02) G, H. Paratype (TS 20201007-04) A. Antennal articles I – IV, dorsal; B. Antennal articles I – IV, ventral; C. Antennal articles V – VIII, dorsal; D. Antennal articles V – III, ventral; E. Antennal articles IX – XIV, dorsal; F. Antennal articles IX – XIV, ventral; G. Antennal article XIV, dorsal; H. Antennal article XIV, ventral. Arrows indicate apical sensillum; arrowheads indicate club-like sensillum. Scale bars: 0.5 mm (A – F); 0.1 mm (G, H).

Figure 9. Dicellophilus praetermissus sp. nov., holotype (TS 20201007-02) A. Left mandible, ventral; B. Maxillae complex, ventral. Scale bars: 0.1 mm (A); 0.5 mm (B).

Figure 10. Dicellophilus praetermissus sp. nov., holotype (TS 20201007-02). A. Forcipular segment, dorsal; B. Forcipular segment, ventral; C. Right condylar process of forcipular coxosternite, dorsal; D. Right forcipular tarsungulum, dorsal; E. Poison calyx, dorsal. The arrow indicates the basal tubercle of the forcipular tarsungulum. Scale bars: 0.5 mm (A, B); 0.2 mm (C); 0.3 mm (D); 0.1 mm (E).

Figure 11. Dicellophilus praetermissus sp. nov., holotype (TS 20201007-02). A. Tergite of leg-bearing segment 40, dorsal; B. Sternite of leg-bearing segment 40, ventral; C. Pretarsus of left leg 40, anterolateral. D. Pretarsus of left leg 2, posterolateral. The arrow indicates a subsidiary spine. Scale bars: 0.5 mm (A, B); 0.1 mm (C, D).

Figure 12. Dicellophilus praetermissus sp. nov. A, B. Holotype (TS 20201007-02) C, D. Paratype (TS 20201007-04) A, C. Ultimate leg-bearing segment and postpedal segment, dorsal; B, D. Ultimate leg-bearing segment and postpedal segment, ventral. Scale bars: 0.5 mm.

Figure 13. Dicellophilus praetermissus sp. nov., holotype (TS 20201007-02). A. Left ultimate leg, dorsal; B. Left ultimate leg, ventral. Scale bars: 0.5 mm.