Mimops occidentalis Chamberlin, 1914

Lewis, John G. E., 2006, On the scolopendromorph centipede genus Mimops Kraepelin, 1903, with a description of a new family (Chilopoda: Scolopendromorpha), Journal of Natural History 40 (19 - 20), pp. 1231-1239 : 1235-1237

Mimops occidentalis Chamberlin, 1914

( Figures 14–20 )

Mimops occidentalis Chamberlin 1914, p 160 , Table 1, Figures 4–7 .

Mimops occidentalis: Attems 1930, p 248 , Figures 329, 330.

Two syntypes: Brazil, Rio de Janeiro TC-532 (1467), unique number 14474, Nathaniel Thayer Expedition 1864, MCZ .

Description of syntypes

Specimen 1. The specimen is very delicate, pre-moult with the old cuticle lifted. It was examined in 70% ethanol and not cleared.

Length 11 mm. With 17 almost glabrous antennomeres.

Head plate as long as wide with sides converging posteriorly ( Figure 14 ), slightly overlapping tergite 1. Chamberlin stated ‘‘longitudinally depressed in caudal region each side of middle’’ but this is not obvious. Ocelli absent.

Clypeus without setae, labrum with low median tooth.

Telopodite of second maxilla with a rudimentary pretarsus (claw). A single seta on the inner surface of telopodite 3 behind the pretarsus.

Coxosternal tooth plates semicircular, each with three minute teeth ( Figures 15, 16 ). Transverse limiting sulci not apparent, although these were illustrated by Chamberlin (1914, Figure 5 ). Forcipular trochanteroprefemur with low median process or tooth.

Tergite 1 with indistinct anterior transverse (ring) suture. Chamberlin noted ‘‘also with a longitudinal furrow each side of the middle extending cephalad from the caudal region and uniting at an angle with its fellow near the middle of the plate from where they continue as a single median furrow to the transverse sulcus’’. These are not clear and their nature is doubtful. They may be bands of pigment.

Trunk flattened (probably squashed) with longitudinal folding so it is not clear whether paramedian sulci are present or not. Only tergite 21 marginate. Sternites with complete paramedian sulci. Sternite 21 trapezoidal ( Figure 17 ).

Coxopleuron with short, digitate process bearing two minute spines ( Figure 18 ) and with numerous small pores which may be in the underlying new cuticle.

Legs 1–20 virtually glabrous, with divided tarsi and hooked pretarsus. The femora, tibiae, and tarsi 1 and 2 each with a small internal distal seta.

Ultimate legs: one loose in tube with three nascent spines seen in profile on prefemur ( Figure 19 ).

Spiracles: only that of segment 3 visible. Viewed from the dorsal side this shows an upper and lower triangular flap ( Figure 20 ).

Specimen 2. Length 10 mm. This specimen lacks antennae and terminal legs. The trunk is round rather than dorsoventrally flattened. Small round spiracles are present on segments 3, 5, 8, 10, 12, 16, 18, and 20.

Remarks

The small size, rounded trunk (seen in specimen 2), lack of sclerotization and only a few poorly developed spines and setae suggest that this is an early adolescens stage similar to that described by Lawrence (1947) for Cormocephalus multispinus ( Kraepelin, 1903) . The presence of coxosternal tooth plates, forcipular trochanteroprefemoral process, spined terminal leg prefemur, bisulcate sternites and divided tarsi, suggest that this is a scolopendrid rather than a cryptopid. The structure of the spiracle of segment 3 seen in specimen 1 is the same as that seen in the first free-living adolescens stadium of Scolopendra gigantea Linnaeus, 1758 (J. G. E. Lewis, unpublished data).

Presumably the absence of ocelli in these specimens prompted Chamberlin to look for relationships within the Cryptopidae . However, in all probability this early stadium was yet to develop ocelli. Lawrence (1947) noted that the ocelli in the first adolescens stadium of the scolopendrid Cormocephalus mutltispinus are represented merely by four reddish orange pigment spots under the ‘‘skin’’. No lenses could be distinguished.

It is concluded that the two syntypes of Mimops occidentalis are an early adolescens stadium of a scolopendrid, too immature for the genus to be determined with certainty.

Figures

Figures 14–20. Mimops occidentalis specimen 1. (14) Head and first three tergites. (15) forcipular coxosternum and right tarsungulum. (16) Detail of left coxosternal tooth plate. (17) Terminal segments, ventral view, pores shown on right coxopleuron. (18) Detail of coxopleural process. (19) Prefemur of ultimate leg. (20) Spiracle of segment 3, dorsal view. sp, spines. Scale bars: 0.5 mm.

Figures 1–7. Mimops orientalis holotype. (1) Head and tergite 1 and 2. (2) Left tarsungulum and part of forcipular coxosternum. (3) Tergite 12. (4) Tergite 21. (5) Sternite 7. (6) Terminal segments, ventral view (coxopleural pores not shown). (7) Detail of coxopleural process. cpl, coxosternal plate; oc, ocellus. Scale bars: 1.0 mm.