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Journal of Paleontology 92(3):478–487
following segment. Prozonites well exposed, depressed, with granular ornamentation. Metazonites raised, divided into three subequal parts by two transverse grooves. Indication of midline lacking (longitudinal cracks on dorsal
surface are not aligned along midline). Longitudinal groove divides short lateral swellings
(?paranota) from remainder of pleurotergite dorsally. Anterior- most and posteriormost part of articulation of swellings with remainder of pleurotergite somewhat invaginated. Lateral swellings extend short distance from sides of pleurotergites. Swellings elongately suboval, covered with small tubercles. Pair of prominent pits (?insertion points for setae), located on posterolateral corner of dorsal surface of swellings. Pits present at least on segments 7, 8, 15, 18, 19, 20, 21, 24, 28, 29, and 31. Pits in each pair obliquely oriented on an irregular raised area. Ozopores apparently lacking. Epiproct (telson) small, longer than segment preceding it, but subequal in length to segment anterior of that segment. Posterior termination of epiproct smoothly rounded, lacking any projections. Surface coarsely granulate. Anal valves not seen (covered by epiproct). Surface of
prozonites and metazonites bearing very small granules, with relatively larger granules on preanal segment. Sternites incompletely seen, but disarticulated from pleur-
otergites, indicating that they were separate in life. Legs stout, length subequal to the length of body segments
(prozonite plus metazonite). Coxae and second segment (presumed prefemur) wide, prefemur longest, with remainder of segments decreasing in length. Two segments preceding epiproct apodous.
Etymology.—The trivial species name is an adjective denoting the location from which the specimen was collected. The gender is neutral.
Remarks.—The head area is difficult to interpret (Fig. 3.1). It is compressed and there has been some displacement due to compression. Preparation has also removed parts of the integu- ment. There is a possibility that the two antennae may overlap somewhat. The lateral swellings described here as possible paranota
could also be conceivably interpreted as ventral portions of pleurotergites, or even as pleurites. Such an interpretation would be unlikely, however, because pleurites and ventrolateral parts of pleurotergites of fossil millipedes are typically seen only when specimens are preserved in ventral or lateral view (e.g., Wilson and Hannibal, 2005, figs. 2, 3, 5, 6). Furthermore, there is no breakage and displacement along the groove that divides the swellings from the pleurotergites in Sinosoma n. gen. as
there is in Pleurojulus. Such breakage has contributed to a longstanding discussion of the nature of the pleurites of Pleurojulus, although Wilson and Hannibal (2005) have provided detailed evidence for there being separate pleurites in that taxon. To complicate this picture, paranota have also been confused with pleurites, as with the paranota of “Pleurojulus steuri” Schneider and Werneberg, 1998 described as pleurites (Wilson and Hannibal, 2005, p. 1106). Paranota as interpreted here also could be interpreted as the
ventral portion of the pleurotergites because what appears to be a border is present on the lateral side of some metazonites. The inflation of the lateral part of the tergites (that is what are described as swellings here), however, argues against such an interpretation. The paired pits on the posterolateral corners of the lateral
swellings of the metazonites are here interpreted as spine bases, in part because of being paired. They do not show any internal structure suggestive of being ozopores. There is a history of confusion between ozopores and spine bases in fossil milli- pedes, and ozopores have been incorrectly described as spine bases in both fossil euphoberiids and palaeosomatids (Hannibal and Krzemin´ ski, 2005, p. 209). Still, it would be unusual for ozopores to be paired, as are the pits of Sinosoma n. gen.
Comparisons to other taxa.—This specimen is similar in a number of ways to the Triassic form Hannibaliulus wilsonae, from the Grès à Voltzia (Anisian) of eastern France, which Shear et al. (2009) assigned tentatively to the Callipodida. Edgecombe (2015, p. 347) subsequently noted the lack of fea- tures that would confirm assignment to that order with certainty. Hannibaliulus wilsonae has up to 44 segments, a small collum, and probably free sternites. The epiproct of H. wilsonae is also similar in shape to, but shorter than, that of Sinosoma n. gen. Shear et al. (2009) also noted a general resemblance of H. wil- sonae to the Paleozoic genus Pleurojulus. This is in great part due to the presence of ?crushed ventral flanges on the former, which resemble the free pleurites of the latter. Division of the dorsal surface of the pleurotergites into
transverse sections is not unusual and is found in a number of unrelated taxa, including the archipolypod Palaeodesmus tuberculata Wilson and Anderson, 2004, and extant polydesmid Polydesmus, which have transverse furrows. In both of those taxa, however, the surface of the metazonite is also subdivided by longitudinal furrows. A single transverse dorsal furrow crosses the pleurotergite of H. wilsonae. The body ring of the Luoping millipede is most like that of
callipodids and chordeumatids in that the sterna are not fused to the pleurotergite. Segment number of the Luopingmillipede (39)
Figure 3. Details of anatomical structures, micro-ornamentation, and appendages of the millipede Sinosoma luopingense n. gen. n. sp., LPI-61593, holotype. (1, 2) Anterior, showing head, collum (whose upper margin is flexed cephalad), short prozonite of the segment following the collum, antennae with five visible antennomeres, (?)gnathocliarium, numerous fine granules on collum, and head (enlarged in 2; black and white arrows point to area delineated by box in 1); (3) lateral view of pleurotergites and sternites (not fused to pleurotergites), and legs; (4, 6) lateral view of pleurotergites and sternites, including (4) two posterolateral pits on lateral swellings and small granules on the prozonite and metazonite surfaces, prominent cracks, lateral swellings (?paranota) separated from remainder of paranota by prominent longitudinal grooves; (5, 7) posterior, showing relatively larger granules on the telson than on other trunk rings; (7) enlarged granular ornament on preanal ring surface; (8–10) enlarged views of the metazonite and prozonite, granules on prozonite are relatively smaller than those on the metazonite; cytoscutes (cuticular platelets) (9) polygonal, five-to-six sided, ~ 10 µ wide; 9 is enlarged from area pointed out by white/black arrows in 10;(10) cracks and depression (white arrow pointed in 4 and 10); (11, 12) enlarged view of lateral swelling (?paranotum) on the metazonite, showing two pits (?spine bases) and granular ornamentation. a1=antennomere1, an=antenna, c=collum, co=coxa, cr=crack, (?)g=(?)gnathocliarium, h=head, lg=longitudinal groove, ls=lateral swelling (?lateral paranotum/paranota), mz=metazonite, p=pits, prfe=prefemur, pz=prozonite, st=sternite, t=telson, tg=transverse groove. 2, 7–12 are scanning electron microscopy images.
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