Lithobius (Sinuispineus) minuticornis, Chang & Pei & Zhu & Ma, 2020

Chang, Xiaodong, Pei, Sujian, Zhu, Chunying & Ma, Huiqin, 2020, An unusual new centipede subgenus Lithobius (Sinuispineus), with two new species from China (Lithobiomorpha, Lithobiidae), ZooKeys 980, pp. 43-55 : 43

Lithobius (Sinuispineus) minuticornis sp. nov. Figs 3 , 4 A-K

Diagnosis.

Antennae composed of 20-23 articles; ocelli 8-10 on each side, arranged in three irregular rows; posterior two ocelli comparatively large. Tömösváry’s organ larger than adjacent ocelli. Commonly 2+2 coxosternal teeth; porodonts lying posterolateral to the lateral-most tooth. Coxal pore formula 3-6, usually 4443 or 5555. Female gonopods with 2+2 moderately small, coniform spurs; male gonopods short and small. Legs 15 considerably modified; prefemur and femur markedly strong, slightly raised inwards, and posterior spurs on dorsal side of femur of male legs 15 curved backward at base of tibia at no more than 45° angle.

Etymology.

The specific name refers to the small, backward-curved posterior spines on the dorsal end of the femur.

Material examined.

Holotype, ♂ (LS02-1) (Fig. 3A ), 12.31 mm long, cephalic plate 1.31 mm long, 1.47 mm wide, Central China, Zhenlei Mountain Forest Park, Pingqiao County, Xinyang City, Henan Province, 32°04.445'S, 114°08.403'E, 256 m a.s.l. August 27, 2017, S. Pei, H. Ma leg. Paratypes, 65 ♀♀, 50 ♂♂ (LS02-1), same date and locality as holotype.

Description.

Body 10.8-16.7 mm long; cephalic plate 1.0-1.5 mm long, 1.1-1.5 mm wide.

Colour: antennae brown to pale yellow from basal to proximal; distal-most article yellow-brown; tergites brown; pleural region and sternites pale greyish yellow; basal and proximal parts of forcipules, forcipular coxosternite, and SS14 and 15 darker; coxa, trochanter, prefemur, femur, and tibia of all legs bluish; tarsus 1 yellow; tarsus 2 yellow-brown.

Antennae: 20-23 articles, commonly 20 articles (Fig. 3A ). Except that length of first antennal article is approximately equal to width of base, length of remaining articles larger than width. Moreover, second article thicker and longer than other articles. Beginning with second article, each article gradually shortened; distal-most article considerably longer than width, 3.0-3.9 times longer as wide. Setae abundant on antennal surface; less so on basal articles; density of setae gradually increase to approximately fifth article, then more or less constant.

Cephalic plate smooth, convex, slightly longer than wide; tiny setae emerging from pores scattered very sparsely over the whole surface; frontal marginal ridge with shallow anterior median furrow; short to long setae scattered along marginal ridge of cephalic plate; lateral marginal ridge discontinuous, posterior margin continuous, wider than lateral marginal ridge; middle of the posterior edge straight.

Eight to ten (commonly nine) oval to rounded ocelli on each side, from small to large, in three irregular rows; posterior two ocelli comparatively large. Ventral ocelli slightly larger than dorsal ocelli, domed, translucent, and usually darkly pigmented (Fig. 3D ).

Tömösváry’s organ (Fig. 3D -To) near the ocelli, at anterolateral margin of cephalic plate moderately larger than the adjoining ocelli, surrounding sclerotised area not obvious.

Coxosternite subtrapezoidal (Fig. 3B, C ); anterior margin narrow; lateral margins slightly longer than medial margins; median diastema moderately deep, narrowly V-shaped; anterior margin with 2+2 slightly larger, acutely triangular teeth; porodonts thicker, with prominent basal protuberance, lying posterior-lateral to lateral-most tooth (Fig. 3B, C ); long, scattered setae on ventral side of coxosternites; longer setae near dental margin.

All tergites smooth, without wrinkles; dorsum slightly convex; tiny setae emerging from sparsely scattered pores over entire surface; near margin bearing a few long setae; TT1 and 14 narrower postero-laterally than antero-laterally, generally trapezoidal; T1 narrower than cephalic plate; T3 approximately equal to cephalic plate; T10 widest. Lateral marginal ridges of all tergites continuous. Posterior margins of TT1, 3, 5, and 7 straight; TT8, 10, 12, and 14 slightly concave. Posterior angles of tergites rounded, without triangular projections. Miniscule setae sparsely scattered over surface.

Posterior side of sternites narrower than anterior, generally trapezoidal, smooth; SS6, 7, 8, 9, and 10 more wider, setae emerging from sparsely scattered pores on surface and lateral margin, with very few long setae sparsely scattered among of them; 2-4 comparatively thick, long setae on both of anterior angles of each sternite; one or two comparatively long, thick setae on both posterior angles of each sternite; more setae on surface of anterior and middle parts than posterior part of each sternite.

Legs relative robust; tarsi fused on legs 1-13; tarsi well-defined on legs 14-15; all legs with fairly long curved claws; legs 1-13 with anterior and posterior accessory spurs; anterior accessory spurs moderately long and slender, forming a moderately small angle with claw; posterior accessory spurs slightly more robust, forming a comparatively large angle with claw; legs 14 and 15 lacking accessory spurs. Short to long setae sparsely scattered over surface of coxa, trochanter, prefemur, femur, and tibia of all legs; more setae on tarsal surface; setae on dorsal tarsal surface slightly shorter than on ventral surface. Legs 14 and 15 in female thicker than anterior pairs; legs 15 in male considerably thicker and stronger than anterior pairs. In females, tarsus2 62.9%-78.8% length of tarsus 1 on legs 15; tarsus 2 5.1-6.5 times longer than its maximum width. In males, tarsus 2 61.3%-70.1% length of tarsus 1 on legs 15; tarsus 2 is 3.5-4.7 times longer than its maximum width. Leg plectrotaxy as in Tables 3 and 4 .

Coxal pores 3-6, in a row, round or slightly oval, greatly variable in size from 18.6 μm to 50.7 μm; coxal pore field set in a relatively deep groove; coxal pore-field fringe with prominence; prominence with 8-12 moderately long setae sparsely scattered over surface.

Female. S15 anterior margin broader than posterior, generally trapezoidal, both of anterior and posterior angles generally rounded, posteriomedially straight, short to long setae sparsely scattered on S15 surface. Sternite of genital segment longer than wide, with surface of its lateral sternal margin well chitinised and posterior margin deeply concave between condyles of gonopods, except for a small, median, approximately rhombic bulge. Relatively long setae scattered over ventral surface of genital segment and slightly more setae near S15. Gonopods: first article fairly broad, bearing 22-24 moderately long setae arranged in three irregular rows; with 2+2 small coniform spurs, inner spur slightly smaller than outer spurs (Fig. 3E ); second article ventrally with 5-7 long setae, arranged in three irregular rows; third article ventrally with one long and one short setae and with a bidentate apical claw (Fig. 4F, G ).

Male. S15 posterior margin narrower than anterior, with both posterior angles rounded; posterior-medially straight, sparsely covered with 31-33 long setae, more than on anterior; sternite of genital segment slightly smaller than in female, usually less sclerotised; posterior margin deeply concave between gonopods, without medial bulge. Long setae scattered on ventral surface of genital segment; fewer setae near S15; fringed with 8-16 longer setae along posterior margin. Gonopods short, appearing as small finger-like bulges, without setae, apically slightly sclerotised (Fig. 4H ).

Legs 15 prominently developed, very thick; prefemur and femur very short (Fig. 4I-K ), posterior spines of dorsal base of femur curved backwards toward base of tibial segment at no more than 45° angle; anterior tibia raised medially inwards. Distal-most anterior spines of dorsal of coxa bearing one or two small teeth; distal-most middle spines of ventral trochanter with a small tooth; posterior part of prefemur considerably larger than anterior part; distal-most part of anterior, middle, and posterior spines of ventral prefemur with 2-4 small teeth; distal-most anterior, middle, and posterior spines of dorsal prefemur with 1-3 small teeth, with both left and right posterior spines arranged opposite each other; femur markedly thick, slightly raised inwards, with posterior spines of dorsal femur curving backwards towards base of tibial segment at no more than a 45° angle (Fig. 4I-K ); distal-most anterior and middle spines of ventral femur with two or three small teeth.

Habitat.

The specimens were collected in a Larix forest at approximately 200 m above sea level. Specimens were living in moderately moist places under roadside stones and litter on the forest floor.

Figures

Figure 3. Lithobius (Sinuispineus) minuticornis sp. nov. (holotype A-D, paratype female E) A habitus, dorsal view B cephalic plate, ventral view C forcipular coxosternite, ventral view D ocelli and Toemoesvary's organ (To), lateral view E posterior segments and gonopods of female, ventral view.

Figure 4. Lithobius (Sinuispineus) minuticornis sp. nov. (paratype female F, G; holotype H-K) F bidentate apical claw of female gonopod, dorsral view G bidentate apical claw of female gonopod, ventral view H posterior segments and gonopods in male, ventral view I femur and tarsus of legs 15, dorsral view J femur and tarsus of legs XV 15, ventral view K posterior spurs of femur of legs 15, ventral view, showing minor teeth.