Macrelmis shoemakei ( Brown, 1971 )

Barr, Cheryl B., 2021, Revision of Macrelmis Motschulsky, 1860 in the Southwestern United States and Northern Mexico with Description of Four New Species (Coleoptera: Elmidae: Elminae), The Coleopterists Bulletin 75 (1), pp. 93-120 : 112

Macrelmis shoemakei ( Brown, 1971) ( Figs. 1, 17–18)

Macrelmis shoemakei was described by Brown (1971) as Elsianus shoemakei from San Felipe Creek, Val Verde County, Texas, and the adjoining state of Coahuila, Mexico. The OMNH Recent Invertebrates Database contains additional records of specimens determined by Brown (1971) from the Mexican states of Morelos, Nuevo Leon, San Luis Potos´ı, and Tamaulipas, and the species has also been reported from the state of Puebla by Curiel and Morrone (2012). In the United States, it is known only from the type locality, where it co-occurs with M. texana .

Diagnosis. Macrelmis shoemakei ( Figs. 17a–b) is a small species, 3.1–3.8 mm long and 1.2–1.5 mm wide ( Brown 1971). Macrelmis moesta ( Figs. 15a–b) overlaps in size (3.4–3.9 mm long, 1.4–1.6 mm wide), but M. shoemakei is less densely granulate and the male genitalia are very different: in M. shoemakei ( Figs. 18a–b) the penis is narrowly spatulate and much longer than the parameres; in M. moesta ( Figs. 16a–b) the penis is abruptly narrowed at the apical 1/ 3 and only slightly longer than the parameres. Macrelmis mexicana ( Figs. 12a–b), which is about the same size or a bit larger, has the pronotal sublateral carinae obscure or lacking; M. shoemakei ( Figs. 17a–b) has prominent pronotal sublateral carinae. In his diagnosis, Brown (1971) compared his new species with M. graniger and M. striata and concluded that it appears to be closest to the latter. He also added a couplet containing M. shoemakei to Hinton’ s key to the Mexican species ( Hinton 1940).

Comments. Macrelmis shoemakei was described by Brown (1971) from a male specimen, and the genitalia were described and illustrated. Although it is not necessary to repeat the description, photographic images of the male genitalia are provided ( Figs. 18a–b). Note that because the penis is so strongly curved, the spatulate shape of the apical third does not appear as pronounced in Fig. 18a as it actually is.