Jianshanopodia decora, Liu & Shu & Han & Zhang & Zhang, 2006

Liu, Jianni, Shu, Degan, Han, Jian, Zhang, Zhifei & Zhang, Xingliang, 2006, A large xenusiid lobopod with complex appendages from the Lower Cambrian Chengjiang Lagerstätte, Acta Palaeontologica Polonica 51 (2), pp. 215-222 : 219-220

Jianshanopodia decora sp. nov.

Figs. 1–4.

Derivation of the name: Decora Latin, alluding to its beautiful and splendid appearance.

Holotype: ELI−J0007 , part and counterpart ( Figs. 1A, 2A , 3B, 4B ).

Type locality and horizon: Helinpu (Chiungchussu) Formation, Yu’anshan Member ( Eoredlichia Zone ), Lower Cambrian. All specimens were collected from Haikou Village , Kunming, Yunnan .

Material.—The material came exclusively form the type locality and all seven specimens were extracted from a grayish−green and grayish−yellow mudstone there. No complete specimens are known, but the fragments can be pieced together to restore a complete picture of the creature.

Diagnosis.—As for genus.

Description.—The body of Jianshanopodia decora comprises three regions: the head, the trunk and the tail. Specimen ELI−J0001 shows the morphology of the head region clearly. It consists of a pair of stout, strongly wrinkled appendages about 40 mm long flanking the anterior, with five cuneiform plates attached along the inner margin of the appendages ( Figs. 1B 1, B 2, 2B 1). A small bradoriid can be observed located on the most anterior frontal plate, in terms of the direction of the cuneiform plate and the location spot of the bradoriid, it is likely to be a captured prey rather than just a chance superimposition ( Figs. 1B 1, B 2, 2B 1). The structure of the anterior gut is noteworthy, appearing to consist of a short, dilatable mouth tube that leads into a funnel−like pharynx surrounded by the bases of the large frontal appendages.

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Irregularly−placed wrinkles in the pharynx appear to be muscles. In the middle of the pharynx there is a mass of prominent circular structure, a structure is similar to the pharyngeal teeth of the tardigrade Echiniscoides ( Barnes et al. 1993) , and here interpreted as such ( Figs. 1B 1, B 3, 2B 2 ).

The worm−like trunk region seems sub−cylindrical in crosssection. It is composed of at least nine segments, and in terms of the whole morphology of the trunk, probably the number of segments was as many as up to 12, each segment bears traces of transverse broad annulations with a density of 80 mm –1 ( Figs. 1A, 2A ). The segments become narrower in the posterior portion of the trunk. Nearly all specimens exhibit stout, sub−triangular appendages that probably projected ventro−laterally from both sides of each segment ( Figs. 1A, 2A, B 1). The appendages are similar in form but decrease in size toward the rear. Two rows of prominent tubercle structures lie on the inferred dorsal side of the appendage from the base to the tip ( Figs. 1A 1, A 2 , 3A 1 –A 3, A 5, 4A 1, A 3). The axial row of tubercle structures is bigger than the lateral ones. Seven big tubercles and four small ones at most are preserved ( Figs. 3A 1 –A 3, 4A 1, A 3). The most striking character of Jianshanopodia decora is the tree−like or lamellate structures projecting from the tubercles. The holotype ELI−J0007A exhibits tree−like branches projecting from the first big tubercle of one appendage ( Figs. 1A 1, 2A , 3B 1, 4B ). The tree bears five branches. The first branch, 10 mm long, is the main body of the tree and it tapers toward the tip. The 2 nd, 3 rd, 4 th, and 5 th pairs of branches all project from the lateral margin of the first branch, there is nearly the same distance between them, about 3 mm long. Similar tree−like branches also occur in the first big tubercle of one appendage of ELI−J0005A; there are also four branches, but the branches are only preserved on one side ( Figs. 3A 4, 4A 2 ). Most likely because of different preservation, the lamellate branches occur on the 4 th large tubercle and the 3 rd small tubercle of the same appendage of ELI−J0005A ( Figs. 3A 5, 4A 3). All the appendages of Jianshanopodia decora possess narrow, transverse annuli. The number of annuli is proportional to the length of appendages ( Figs. 1A 1, A 2, 2A , 3A 3, 4A 1). The tips of the appendages are moderately pointed, but there is no convincing evidence for the presence of terminal claws.

As in most lobopods ( Chen et al. 1995; Bergström and Hou 2001), there is a fine canal running centrally through the entire length of each appendage in Jianshanopodia decora . In specimens ELI−J0005A and ELI−J0007A, the fine canal extends centrally to the branches of appendages ( Figs. 1A 1, 2A , 4A 1, A 3, B). The fine canal branches out from the ventral canal of the body cavity, which is expressed in the body as a dark−brown tube ( Figs. 1A 1, 2A ).

The gut appears to run through the entire trunk region ( Figs. 1A 1, A 2 , B 1, 2A, B 1), usually preserved as a flattened band lying near the ventral margin. No evidence for the anus is present. In most specimens, two rows of prominent, dark, reniform structures with internal anastomoses are situated on either side of the gut ( Figs. 1A 1, A 2, 2A , 3A 6, C). In specimen ELI−J0004B, linear and elongate tube−like internal structures are observed ( Fig. 3C 2 ). Given their association with the gut ( Figs. 1A 1, A 2, 2A , 3A 6, B 2), they are likely to represent mid−gut diverticula, as occur in the stem group arthropod Pambdelurion ( Budd 1997, 1999) and many Cambrian arthropods such as Naraoia ( Whittington 1977) .

The tail region of Jianshanopodia decora is not well preserved. After careful preparation, we were able to observe the outline of three lobes arranged into a tail fan, one is located in the midline, the two others on both sides. The middle one is bigger and stronger than the others ( Figs. 1A 1, A 3, 2A ).

Figures

Fig. 2. Lower Cambrian xenusiid lobopod Jianshanopodia decora gen. et sp. nov., from Haikou, Kunming, Yunnan, China, camera lucida drawings of the specimens illustrated on Fig. 1. A. A sketch drawing of the specimen ELI−J0005A from Fig. 1A1, demonstrating all available features of a new species. B. ELI−J0001. B1, the anterior part of Jianshanopodia decora redraw from Fig. 1B1, note the strongly wrinkled frontal appendages, mouth tube and funnel−like pharynx structures; B2, enlargement of the funnel−like pharynx structures of the same specimen, from the Fig. 1B3.

Fig. 4. Camera lucida explanatory drawings of the specimens of Jianshanopodia decora gen. et sp. nov. from Fig. 3. A. ELI−J0005A; A1, enlargement of tubercles of one of the appendages (see Fig. 3A3); A2, different branches of the appendages (see Fig. 3A4); A3, the lamellate branches (see Fig. 3A5). B. ELI−J0007A, the tree−like branches of the holotype (see Fig. 3B1).