Palaeolenus douvillei Mansuy, 1912

Zhao, Wenyu, Liu, Jianni & Bicknell, Russell D. C., 2020, Geometric morphometric assessment of Guanshan trilobites (Yunnan Province, China) reveals a limited diversity of palaeolenid taxa, Palaeontologia Electronica (a 22) 23 (2), pp. 1-15 : 9-10

Palaeolenus douvillei Mansuy, 1912

Figure 5

1912 Palaeolenus douvillei Mansuy. Mansuy , p. 29, pl. 3, fig. 6a-d; pl. 4, fig. 1a-d.

1912 Palaeolenus lantenoisi Mansuy. Mansuy , p. 29, pl. 4, fig. 2a-e.

1941 Palaeolenus douvillei Mansuy. Lu , p.83, pl. 1, fig. 14.

1941 Palaeolenus tingi Lu. Lu , p.83, pl. 1, fig. 15 a-b.

1941 Palaeolenus lantenoisi Mansuy. Lu , p.84, pl. 1, fig. 13a-c.

1965 Palaeolenus douvillei Mansuy. Lu, Chang, Chu, Chien, and Hsiang. , p. 82, pl. 12, fig. 9.

1965 Palaeolenus lantenoisi Mansuy. Lu, Chang, Chu, Chien, and Hsiang. , p. 83, pl. 12, figs. 11, 12.

1965 Palaeolenus tingi Lu. Lu, Chang, Chu, Chien, and Hsiang , p. 84, pl. 12, figs. 13

1978 Palaeolenus lantenoisi Mansuy. Zhou and Lin , p. 149, pl. 24, figs. 7-9.

1980 Palaeolenus tingi Lu. Chang, Lu, Chu, Chien, Lin, Zhou, Zhang, and Yuan. , p. 231, pl. 71, figs. 4-6.

1980 Palaeolenus lantenoisi Mansuy. Chang, Lu, Chu, Chien, Lin, Zhou, Zhang, and Yuan , p. 230, pl. 71, figs. 1-3; pl. 72, fig. 1.

1988 Palaeolenus lantenoisi Mansuy. Yi , p. 31, pl. 1, figs. 1-18.

2004 Palaeolenus douvillei Mansuy. Lin and Peng , p. 35, pl. 1, figs. 1-15; pl. 2, fig. 3.

2008 Palaeolenus douvillei Mansuy. Luo, Li, Hu, Fu , Hou, Liu, Chen, Li, Pang, and Liu, p. 74, pl. 18, figs. 1-4.

2008 Palaeolenus lantenoisi Mansuy. Luo, Li, Hu, Fu , Hou, Liu, Chen, Li, Pang, and Liu, p. 75, pl. 18, figs. 7-16.

2013 Palaeolenus douvillei Mansuy. Hu, Zhu, Luo , Steiner, Zhao, Li, Liu, and Zhang, p. 96, figs. 120, 121.

2013 Palaeolenus lantenoisi Mansuy. Hu, Zhu, Luo , Steiner, Zhao, Li, Liu, and Zhang, p. 96, figs. 122, 123A-N.

Referred material. LBS-5, LBS-113, LBS-116, LBS-121, LBS-123, LBS-125, LBS-126, LBS-129, LBS-130, LBS-131, LBS-132, LBS-135, LBS-139, LBS-140, LBS-141, LBS-142, LBS-145, LBS-151, LBS-154, LBS-155, LBS-160, LBS-177, LBS-185, LBS-187, LBS-216, LBS-217, LBS-224, LBS-267, LBS-301, LBS-306, LBS-310, LBS-312, LBS-313, LBS-315, LBS-319, LBS-321, LBS-325, LBS-381, LBS-394, LBS-397, LBS-399, LBS-401, LBS-405, LBS-408, LBS-410, LBS-411, LBS-413, LBS-417, LBS-422, LBS-427, LBS-437, LBS-440, LBS-444, LBS-454, LBS-459, LBS-461, LBS-472, LBS-474, LBS-517, LBS-523, LBS-524, LBS-528, LBS-531, LBS-548, LBS-549, LBS-553, LBS-556, LBS-561, LBS-566, LBS-567, LBS-603, LBS-617, LBS-626, LBS-629, LBS-661, LBS-669, LBS-688, LBS-690, LBS-718, XLC- 0021, XLC-0028, XLC-0407, XLC-0427, XLC-0904, XLC-0915, XLC-0936, XLC-0977, XLC-0991, XLC-1000, XLC-1100, XLC-1101, XLC-1117, XLC-1124, XLC-1267, XLC-1274, XLC-1276, XLC-1290, XLC-1300, XLC-1307, XLC-1342, XLC-1350, XLC-1364, XLC-1434, XLC-1445, XLC-1457, XLC-1827, XLC-1837, XLC-1844, XLC-1855, XLC-1976, XLC-2000, XLC-2001.

Diagnosis. Palaeolenus with long (tr.) ocular ridges, short (exs.) palpebral lobes, oblique to the axial furrow with a moderately robust glabella and a relatively broad (tr.) fixigena.

Description. The morphologically mature exoskeleton is ovate in outline, micropygous and 1-2 cm long (sag.). Cephalon is semi-elliptical. Ocular ridge is wider (tr.) compared to palpebral lobe length (sag.) and the relative width (tr.) of the ocular ridge and palpebral lobe length (sag.) are size-related. Smaller specimens have wider (tr.) ocular ridge compared to palpebral lobe length (sag.) ( Figure 5 A-D), which contrasts larger specimens ( Figure 5 E-I). Glabella shape is variable: most specimens have a rectangular-shaped glabella that is expanded anteriorly in some larger specimens ( Figure 5 G-H). It is notable that some specimens only have a rectangular-shaped glabella without the expanded anterior ( Figure 5A, D ), and some specimens have a subcylindrical glabella ( Figure 5I ). Three or four pairs of glabellar furrows present. Fixigena is wider (tr.) than the librigena. The postero-lateral projection is long (sag.) and narrow (tr.). Most specimens have 13 thoracic tergites with larger specimens displaying 14 or 15 tergites. Pleural lobe is slightly wider (tr.) than axial lobe. Semi-elliptic pygidium is divided into two parts by one transverse furrow. Its axial lobe is relatively wide (tr.) compared to its pleural lobe.

Remarks. The geometric morphometric results show that cranidia of Palaeolenus douvillei and P. “lantenoisi ” occupy the same region of morphospace. Palaeolenus douvillei therefore shows substantial variation where most studied specimens have 13 thoracic tergites, indicative of P. “lantenoisi ”, while large specimens have 14 or even 15 thoracic tergites, are indicative of P. douvillei (sensu Mansuy, 1912). Compared with Megapalaeolenus deprati , the palpebral lobes of P. douvillei are consistently shorter (sag.) or at most similar in length (tr.) to ocular ridges, with larger specimens having proportionally longer palpebral lobes than smaller specimens. The length (sag.) of the anterior border is variable and not size-related.

Figures

FIGURE 5. Articulated specimens of Palaeolenus douvillei from the Longbaoshan and Xinglongcun sections. A. LBS- 548. B. XLC-1960. C. LBS-566. D. XLC-2000A. E. LBS-661A. F. LBS-151. G. XLC-0904. H. LBS-629. I. LBS-177. Scale bars equal 3 mm. White arrows indicate the thorax-pygidium boundary.