Lochmanolenellus cf. primus

Webster, Mark & Bohach, Lisa L., 2014, Systematic revision of the trilobite genera Laudonia and Lochmanolenellus (Olenelloidea) from the lower Dyeran (Cambrian Series 2) of western Laurentia, Zootaxa 3824 (1), pp. 1-66 : 32

Lochmanolenellus cf. primus 1

Fig. 10.1–10.3

1952 Wanneria mexicana prima Lochman in Cooper et al. (part), pl. 18, fig. 1 only.

Material. USNM 115683 (Fig. 10.2; also figured by Lochman in Cooper et al., 1952, pl. 18, fig. 1) and USNM 115684 (a lot collection of two limestone slabs, both bearing several cephala). Quantitative morphometric and/or qualitative descriptive data were recorded from first-hand examination of USNM 115683 and the three best preserved cephala from USNM 115684.

Occurrence. MEXICO: Sonora State: USNM locality 801c. See Lochmanolenellus primus for details.

Discussion. USNM 115683 and USNM 115684 from the Caborca area were listed as paratypes of “ Wanneria mexicana prima ” by Lochman (in Cooper et al., 1952, p. 97). All these specimens are very worn and mostly/ entirely exfoliated, and none would be expected to preserve the prosopon or the lateral swellings on the glabella characteristic of the genus (although USNM 115683 does show traces of the reticulate prosopon in the anterior cephalic border furrow [Fig. 10.3]). However, all cephala in lot collection USNM 115684 bear genal and intergenal spines that flare quite strongly laterally, as do at least the genal spines of USNM 115683 (the intergenal spines of this specimen are not preserved; Fig. 10.2). USNM 115683 and at least one specimen within lot collection USNM 115684 (Fig. 10.1) seem to possess an extraocular platform (the other specimens within the lot collection are too poorly preserved to determine the state of this character). Such traits are indicative of Lochmanolenellus . The placement of the genal spine bases and the orientation of the distal portion of the posterior cephalic margin of these specimens are similar to Lochmanolenellus primus , with which the specimens co-occur. The best preserved specimens (Fig. 10.1, 10.2) differ from the holotype of Lo. primus in possessing a proportionally wider (tr.) extraocular area with a more subdued extraocular platform, a less strongly dorsally rounded anterior cephalic border, and proportionally shorter ocular lobes (with posterior tips located transversely opposite the lateral margins of L2 rather than S1). However, these two specimens are more than twice as large as the holotype of Lo. primus (sagittal cephalic lengths approximately 19.8 mm and 22.4 mm, respectively, versus approximately 9.7 mm for the holotype), and the differences might be attributable to ontogenetic allometry given the known patterns of shape change within other species of the genus (see following). As a result of these morphological differences and ambiguities, all these specimens are herein conservatively identified as Lo. cf. primus 1.