Echiniscus semifoveolatus Ito, 1993

Qiao, Penghai, Zhang, Pin, Sun, Xizhai & Li, Xiaochen, 2013, Echiniscus semifoveolatus (Heterotardigrada: Echiniscidae), a newly recorded species from China, Zootaxa 3718 (2), pp. 183-192 : 184-189

Echiniscus semifoveolatus Ito, 1993

(Fig. 2–4, Table 1 )

Material examined. Specimens with the slide numbers wy1641 and wy1874 were collected from Tongmu Village, Xingcun Town, Wuyishan City, Fujian (27°44′56″N, 117°40′51″E) at 782m above sea level; specimen with the slide number wy1409 was collected from Wuyishan Scenic Spot, Wuyishan City, Fujian (27°37′37″N, 117°56′44″E) at 427 m above sea level; specimens with the slide numbers jg074, jg033 were collected from Huangyangjie, Mt. Jinggang, Jiangxi (26°32′42″N, 114°08′55″E) at 890 m above sea level. A total of five specimens were collected; all female.

Description. Small in size (body length ranged from 131.1 to 155.7 Μm). Black eyes present. Body colour brown. Cuticular sculpture composed of irregular polygon-shaped depressions; most are pentagon- or hexagonshaped, a few approximately rounded. The depressions on the scapular and terminal plates are much larger than those on the other dorsal plates including the cephalic plate. The largest depression with a diameter of 3.0 Μm, while the smallest depression with a diameter of 1.6 Μm. The dorsal plates consist of the cephalic plate, scapular plate, first median plate, first paired plates, second median plate, second paired plates, third median plate and the terminal plate. The terminal plate with the usual incisions, not faceted. All plates undivided. Intersegmental lateral plates absent. The cephalic appendages consist of the internal buccal cirrus, cephalic papilla, external buccal cirrus, cirrus A, and the clava. The lateral appendages include cirrus C, cirrus D, and cirrus E; cirrus B unilateral, tiny, and present only in one specimen. All lateral cirri very robust. The dorsal appendages include, not only the traditional dorsal spines of some Echiniscus species B d, C d and D d, but also spines that arise from the posterior margin of the scapular plate (spines B md) (when present, up to five), a pair of spines present at the posterior margin near the central suture of the first paired plates (C md) and the second paired plates (D md) (Figs. 2–3). Ventral side of the body smooth without any plate or sculpture ( Fig. 4 ). A spur present on the external side of the first pair of legs. A papilla present on the external side of the hind legs. Dentate collar present on the hind legs with 9 teeth (Fig. 2c). Spurs that pointed towards the base of the claw present on the internal claws on all legs (Fig. 2b, c). The measurements of some structures of the studied specimens are given in Table 1 .

-, directions not suitable for measurement; B d, dorsal spine B; C d, dorsal spine C; D d, dorsal spine D; md, median spines on dorsal plate; B md, spines arise from the posterior margin of the scapular plate; C md, spines in pair arise from the posterior end of the suture between the first paired-plates; D md, spines in pair arise from the posterior end of the suture between the second paired-plates.

Eggs unknown.

Remarks. The Chinese specimens have provided additional information about this rare species, such as the variation in the number of dorsal spines at the posterior margin of the scapular plate, and the presence or absence of spine B and the cuticular sculpture. In our Chinese specimens the number of dorsal spines that arise from the posterior edge of the scapular plate varies from zero to five ( Fig. 3 ), whilst the Japanese type specimen (see: Ito, 1993; page 8, fig 8) has two spines with symmetrical arrangement (referred to by the old notation of “segmental plate 1, spine B2”, Ito, 1993). The distance between the spines also varies, a character we consider to be individual variability. Ito (1993) describes the cuticular sculpture of the Japanese specimens “round depressions” on the “head plate and segmental plates 1 and 4”. In our Chinese specimens we interpret the sculpturing as composed of irregular polygon-shaped depressions over all the dorsal plates but larger on the scapular (Ito, 1993 ≡ segmental plate 1) and terminal plates (Ito, 1993 ≡ plate 4). In the Japanese type material Ito (1993) reported the presence of three median plates (though the third median plate was not drawn – see: Ito, 1993; figure 8), with “branch-like transversal ridges” on segmental plates 1, 2 and the three median plates that were also described as “covered with tiny and dark granules”. In our Chinese specimens the transversal ridges are absent and the “tiny dark granules” are revealed as cuticular depressions similar, though smaller, to those on the scapular and terminal plates.

Samples from the Mt. Jinggang, Jiangxi (26°32′42″N, 114°08′55″E) at 890 m asl provided, in addition to E. semifoveolatus , three more new species belonging to two classes and three genera Hypechiniscus , Echiniscus , and Diphascon (Adropion) . These will be reported elsewhere.

FIGURE 2. E. semifoveolatus Ito (slide number: jg074). a, Habitus in dorsal view focused to show the dorsal plates, cuticular sculpture, lateral and dorsal appendages; b, claws on the 3rd pair of legs, showing the spur on the internal claws; c, hind leg, showing the dentate collar. Scale bars: a, 30 µm; b, 5µm; c, 10 µm.

Up to now, a total of 37 species of the genus Echiniscus have been reported from China (Pilato et al., 2008; Beasley & Miller, 2012; Gao et al., 2012; Rahm, 1936a, b, 1937; Beasley, 1999; Beasley & Cleveland, 1996; Beasley et al., 2006; Yang, 2002, 2003; Li et al., 2005, 2007, 2008; Wang, 2005; Pilato, 1974; Séméria, 1994). In the original descriptions of E. angolensis da Cunha and do Nascimento Ribeiro, 1964 and E. cavagnaroi Schuster and Grigarick, 1966 the presence of cirri B and D are described as absent. However, specimen attributed to these two species from Yunnan, China (Yang, 2002) both bear cirri B and D, and therefore the existence of these species in China is dubious.

A key to all Chinese species of the genus Echiniscus is given below and includes the newly recorded species.

Figures

FIGURE 3. Habitus of E. semifoveolatus Ito, 1993 in dorsal view focused to show the variability in the arrangement of lateral and dorsal appendages. Slide numbers: a, wy 1641; b, wy 1409; c, jg 033; d, wy 1874. Scale bars: a – d, 30 µm.

FIGURE 4. Ventral side of E. semifoveolatus (slide number: jg 074) focused to show the smooth surface of the ventral side. The arrow points at the genital pore. Scale bar: 30 µm.

Tables

TABLE 1. Measurements (in µm) of E. semifoveolatus Ito, 1993.

characters	Wy1641-1	Wy1874	Wy1409	Jg074	Jg033
Body length	131.1	145.7	155.7	136.5	153.8
Body width	64.3	75.8	78.7	68.4	79.2
Internal buccal cirrus	9.8	11.0	11.3	12.4	9.7
Cephalic papilla	6.2	5.0	6.3	5.1	5.0
External buccal cirrus	9.0	11.0	13.4	11.2	11.1
Clava	4.3	4.9	5.1	5.3	5.2
Cirrus A	26.8	26.0	34.7	26.2	26.6
Cirrus B	-	5.8	-	-	-
Cirrus B d	-	5.2	4.6	7.5	4.7
Cirrus B md	-	4.5	-	4.6	5.3
Cirrus C	11.1	13.6	15.0	15.3	13.3
Cirrus C d	10.1	11.3	12.1	11.9	11.8
Cirrus C md	5.7	11.5	8.4	9.3	9.8
Cirrus D	15.0	19.8	18.7	17.0	16.8
Cirrus D d	13.2	15.7	15.5	15.7	16.8
Cirrus D md	7.3	12.5	10.7	9.4	9.6
Cirrus E	15.2	15.1	14.8	13.8	16.2
Claws on leg I	7.6	7.2	8.2	6.8	6.4
Claws on leg II	7.8	7.7	9.3	6.9	6.4
Claws on leg III	8.0	8.0	9.4	7.0	6.7
Claws on leg IV	8.5	8.9	10.6	7.7	8.2