Scolopendrellopsis glabrus, Jin, Ya-Li & Bu, Yun, 2018

Jin, Ya-Li & Bu, Yun, 2018, First record of Scolopendrellopsis from China with the description of a new species (Myriapoda, Symphyla), ZooKeys 789, pp. 103-113 : 104-110

Scolopendrellopsis glabrus sp. n. Figs 1, 2, 3. Tables 1, 2, 3

Diagnosis.

Scolopendrellopsis glabrus sp. n. is characterized by the short central rod on head, 3rd tergite not divided and with only weak middle indentation, rod-like sensory organs with setae surrounded on dorsal side of 3 rd– 17th antennal segments, cavity-shaped organs on dorsal side of subapical 5-6 antennal segments, mushroom-shaped organs at lateral side of subapical 4-7 segments and bladder-shaped organs on subapical 3-6 antennal segments, first pair of legs longer than the tarsus of the last pair of legs, cerci short and covered with a low number of straight setae.

Material examined.

Holotype, female (slide no. ZJ-GTS-SY2012017) (SNHM), China, Zhejiang Province, Gutian Mountain, extracted from soil samples in broad-leaved forest, Alt. 1000 m, 29°15'N, 118°06'E, 11-IV-2012, coll. Y. Bu et al. Paratypes, 2 female (slides nos. ZJ-GTS-SY2012010, ZJ-GTS-SY2012016) (SNHM), same date as holotype; 1 female (slide no. ZJ-GTS-SY2012051) (SEM), ibidem, 14-X-2012; 2 females (slides nos. ZJ-GTS-SY2012055, ZJ-GTS-2012060) (SNHM), ibidem, 17-XI-2012; 1 female (slide no. ZJ-GTS-SY2013015) (SNHM), ibidem, 24-IV-2013; 1 male (slide no. JS-WX-SY2017001) (SNHM), China, Jiangsu Province, Wuxi, Daji Mountain, extracted from soil samples in bamboo forest, Alt. 5 m, 31°32'N, 120°12'E, 9-X-2017, coll. Y. Bu. Other material (SNHM): 8 juveniles with 8-10 pairs of legs (slides nos. ZJ-GTS-SY2012002, ZJ-GTS-SY2012004, ZJ-GTS-SY2012006, ZJ-GTS-SY2012012-ZJ-GTS-SY2012015, ZJ-GTS-SY2012019), same data as holotype; 1 juvenile with 10 pairs of legs (slide no. ZJ-GTS-SY2012023), ibidem, 19-VI-2012, coll. Y. Bu et al; 6 juveniles with 8-11 pairs of legs (slides nos. ZJ-GTS-SY2012028-ZJ-GTS-SY2012032, ZJ-GTS-SY2012039), ibidem, 15-VII-2012, coll. Y. Bu et al; 2 juveniles with 9 and 10 pairs of legs (slides nos. ZJ-GTS-SY2012046, ZJ-GTS-SY2012051), ibidem, 14-X-2012, coll. Y. Bu et al; 2 juveniles with 10 and 9 pairs of legs respectively (slides nos. ZJ-GTS-SY2012052, ZJ-GTS-SY2012055), ibidem, 17-XI-2012, coll. Y. Bu et al; 3 juveniles with 8-10 pairs of legs (slides nos. ZJ-GTS-SY2012064-ZJ-GTS-SY2012066), ibidem, 12-XII-2012, coll. Y. Bu et al; 1 juvenile with 8 pairs of legs (slide no. ZJ-GTS-SY2013004), ibidem, 23-II-2013, coll. Y. Bu et al; 6 juveniles with 8-10 pairs of legs (slides nos. ZJ-GTS-SY2013005, ZJ-GTS-SY2013009, ZJ-GTS-SY2013011, ZJ-GTS-SY2013013-ZJ-GTS-SY2013015), ibidem, 27-III-2013, coll. Y. Bu et al; 1 juvenile with 9 pairs of legs (slide no. HN-SY-SY2017001), China, Hainan Province, Sanya, Yalong bay tropical paradise forest park, extracted from soil samples in bamboo forest, Alt. 67 m, 18°15' N, 109°37'E, 22-III-2017, coll. Y. Bu.

Description.

Adult body 1.57 mm long in average (1.45-1.65 mm, n = 8), holotype 1.65 mm (Figure 1A). Head longer than wide, length 145-175 μm, width 133-170 μm, with widest part a little behind the middle on a level with the points of articulation of mandibles. Central rod distinct and with anterior part absent, length 45-49 μm, approximately one-third of head. Dorsal side of head covered with sparse setae of different length, longest setae (12-17 μm) located at the anterior part of head, approx. 3.0 times as long as central ones (4-5 μm). Cuticle around Tömösváry organ and anterolateral part of head with rather coarse granulation. Central and posterior part of head with dense pubescence (Figs 1B, 3A).

Tömösváry organ oval, maximum diameter 17.0-22.5 μm, somewhat shorter than the greatest diameter of 3rd antennal segment (20-23 μm), opening at front position, with diameter (4-5 μm) approx. one-fourth of 3rd segment of antennae (Figs 1F, 3A).

Mandible with eleven teeth and divided into two parts by a gap, with five anterior and six posterior teeth respectively. First maxilla has two lobes, inner lobe with four hook-shaped teeth, palp bud-like with two distal points close to outer lobe (Figure 3B). Anterior part of second maxilla with many small protuberances and posterior part with sparse setae. Cuticle of second maxilla covered with pubescence (Figure 2A).

Antennae 15-19 segments (16 in holotype), length 250-350 μm (320 μm in holotype), approx. 0.2 of the length of the body. First segment cylindrical, greatest diameter a little wider than long (20-26 μm: 16-25 μm), with four setae in one whorl, the longest seta (6-11 μm) inserted at the inner side and distinctly longer than outer ones (5-8 μm). Second segment wider (20-30μm) than long (18-22 μm), with six or seven setae evenly inserted around the segment and inner setae (6-10 μm) a little longer than outer ones (5-7 μm). Chaetotaxy of 3rd segment similar to preceding ones (Figure 3C). Setae on the basal segments 1-3 are slender and on proximal and distal segments rather short. Basal and median parts of the antennae with only primary whorl of setae, in subapical segments one or two minute setae present in secondary whorl (Figure 3E). Four kinds of sensory organs present on antenna: rod-like sensory organs with setae surrounded present on dorsal side of 3 rd– 17th segments (Figs 1C, 3C, 3D); cavity-shaped organs present on dorsal side of subapical 5-6 segments (Figs 1E, 3D); mushroom-shaped organs present on lateral side of subapical 4-7 segments and bladder-shaped organs on subapical 3-6 segments (Figs 1D, 1E, 3D, 3E). Apical segment subspherical, width 21-22 μm, length 19-20 μm, with 10-12 short setae and wide connection to preceding segment and with two fire-shaped and three baculiform organs present on apex (Figs 1D, 3D, E). All segments covered with short pubescence. Chaetotaxy and sensory organs of antennae are given in Table 1.

Trunk: seventeen dorsal tergites present, with 6th, 9th, 12th, and 15th tergites transversely divided, longer than preceding ones (Figs 2E, 2G, 2H, 2J). Intertergal zones between former and later tergites present, except for 14th and 15th, 16th, and 17th tergites. Tergites 2 th– 13th and 15th each with one pair of slender chitinous processes, slightly finger-like. Basal distances between processes are approx. the same length as their length from base to tip, which is longer than its basal width. All tergites pubescent and the margins of apical part of processes ornamented with rowed coarse granules. Apical seta on processes slightly anteriorly located and anterolateral setae slightly longer than other setae. No seta between apical and inner basal setae (Figs 2 B– 2H).

Tergites: 1st tergite reduced to a narrow short plate with a pair of diagonal bands and with six short setae in a row (Figs 2B, 3A). Second tergite complete, broader than long, with two slender posterior processes, 1+1 axial setae and 7+6 lateral setae (asymmetrically lack one lateral seta in holotype, 7+7 lateral setae in all paratypes), with anterolateral setae slightly longer than others, processes approx. 1.5 times as long as broad, basal distance between processes approx. the same as long as their length (Figs 2B, 3A). Third tergite entire with weak middle indentation, broader and longer than preceding one with the ratios mentioned nearly 1.6 and 0.8 respectively, 2+2 axial setae and 9+9 lateral setae (Figs 2C, 3A). Fourth tergite broader than 3rd tergite, with the ratios approx. 1.2 and 0.9 respectively, 2+2 axial setae and 6+6 lateral setae (Figs 2D, 3A). The shape and chaetotaxy of 5 th– 7th, 8 th– 10th, and 11 th– 13th tergites similar as 2 nd– 4th tergites. 14th tergite without processes and relevant area replaced by two roundish tubercles with four setae inserted on (Figure 2I). 15th tergite shorter than 3rd, 6th, 9th, and 12th tergites, with smaller processes (Figs 2C, 2E, 2G, 2H, 2J). Chaetotaxy and measurements of tergites are given in Tables 2 and 3.

Legs: all twelve pairs of legs with claws.1st pair of legs short, 3-segmented, length 35-45 μm, not more than the length of 2th pair of legs, but longer than the tarsus (30-32 μm) of last pair of legs; femur at least 1.2 times wider than long (15-22 μm: 12-15 μm), with two setae at the outer side; tibia approx. 1.4 times wider than long (14-20 μm: 10-14 μm), with dorsal seta (8-10 μm) longer than ventral one (4-6 μm); tarsus longer than wide (12-19 μm: 10-17 μm), with four setae, three dorsal (5-7 μm) and one ventral (6-8 μm); claws simple and the anterior one a little larger and broader than posterior (Figs 1I, 3F). 12th pairs of legs approx. three-fourths as long as the length of the head. Trochanter longer than wide (30-40 μm: 23-31 μm), with 6 subequal setae; femur approx. as long as wide (19-25 μm: 19-25 μm), with three setae transversely, one (10-14 μm) distinctly longer than other two (6-9 μm); tibia longer than wide (19-25 μm: 15-21μm), with four dorsal setae, of which one (10-14 μm) distinctly longer than others (6-9 μm); tarsus not more than 3 times as long as wide (30-32 μm: 11-15 μm) with 8-9 setae, of which 3 are protruding and 2 depressed, longest setae (12 μm) approx. as long as the greatest width of the joint. Claws rather curved, anterior one a little longer and broader than posterior one (10 μm: 8 μm) (Figure 3G). All legs covered with dense pubescence (Figs 1I, J, K).

Coxal sacs present at bases of 3 rd– 9 th pairs of legs, fully developed, each with 3 setae (Figs 1J, 1K).

Styli present at base of 3 rd– 12th pairs of legs, reduced into small knobs with tuft of setae, on 9 th– 12th legs larger than on former legs, especially on 11th legs (5-6 μm), distinctly longer than anterior ones (2-4 μm) (Figs 1G, 1H, 3J).

Sense calicles with smooth margin to pit, length nearly two times longer than outer diameter (25-35μm: 12-16μm). Sensory seta inserted in the center of cup, extremely long, length 100-120 μm, at least 8.5 times longer than other two lateral setae (11-14 μm, 7-10 μm respectively) that inserted at the edge of cup (Figs 3H, I).

Cerci subuliform, short, approx. half as long as head, somewhat shorter than 12th pairs of legs, length at least three times as long as its greatest width (80-95 μm: 25-30 μm), sparsely covered with long and straight setae, with the longest one (12.5-17 μm) approx. half of the greatest width of the cerci, terminal area (10-13 μm) short, with length at most half of the greatest width of the cerci and circled by 6-8 layers of curved ridges. Terminal setae length 18-20 μm, distinctly longer than terminal area (Figure 1L, 3K).

Etymology.

The species name glabrus , meaning bald, to indicate the lower number of setae on cerci.

Distribution.

China (Zhejiang, Jiangsu, Hainan).

Remarks.

Scolopendrellopsis glabrus sp. n. is similar to S. hirta (Scheller, 1971) and S. spinosa (Sheller, 1979) in the shape of 3rd tergite which is not divided, shape of processes on tergites, shape of sensory organs on antennae. It differs from the latter two species in the absence of anterior part of central rod (anterior part present but indistinct in S. hirta , distinct in S. spinosa ), chaetotaxy of the 2nd and 3rd tergites (with four and five lateromarginal setae in S. glabrus respectively, five and six in the other two species), cerci with lower number of setae (more setae in S. hirta and S. spinosa ), all setae on cerci long and straight (setae on inner side of cerci slightly curved in S. hirta , most setae on cerci short and curved in S. spinosa ). It is also similar to the worldwide species S. subnuda in the shape of the first three tergites, number of lateromarginal setae of the 3rd tergite, shape and number of setae of the cerci, but differs in the absence of anterior part of central rod (anterior part present in S. subnuda ), apical seta on processes slightly anteriorly located (rather close to the apex in S. subnuda ).