Margarinotus (Paralister) ephemeralis Caterino, 2010

Caterino, Michael S., 2010, A Review of California Margarinotus Marseul (Coleoptera: Histeridae: Histerinae: Histerini), with Descriptions of Two New Species, The Coleopterists Bulletin 64 (1), pp. 1-12 : 3-5

Margarinotus (Paralister) ephemeralis Caterino , new species ( Figs. 1 , 2A–C , 3 )

Types. Holotype Male. “ CA: Santa Barbara

Co. , 34.7070°N, 120.0421°W, UC Sedgwick Reserve , i.16.2005, M. Caterino, burrow Spermophilus ”, CBP0023903 ; SBMN. Paratypes (4) : 1 female, same data as holotype, gold coated for SEM, CBP0023900 ; 2 males: “ CA: Santa Barbara Co., 34.6825°N, 120.0445°W, UC Sedgwick Reserve , i.15.2005, M. Caterino, in vernal pool”, CBP0023786 , CBP0023788 ; 1 male: “Calif., L.A. Co., Benedict Cyn., Jan 12 1968 E. Giesbert, Coll.”, LACM ENT 266292 ; deposited in SBMN, CASC, FMNH, LACM.

Diagnosis. This species is very similar to M. remotus . Together these are the only California Margarinotus exhibiting a single lateral pronotal stria (the outer stria being completely absent; Fig. 1C ). Externally, M. ephemeralis can usually be separated by the pronotal punctation, where it has irregular punctures mediad of the apical half to two-thirds of the inner pronotal stria, this group of punctures approximately as wide as the space between the pronotal margin and lateral stria. These are both denser and occupy slightly more space than in M. remotus . It has an additional cluster of pronotal punctures on each side just behind the anterior stria, approximately posterad eye, which is very inconspicuous or lacking in M. remotus . In the male, in dorsal view ( Fig. 2A ), the apical half of the median lobe of M. ephemeralis is narrower, and is markedly narrowed in the apical one-fifth in partic- ular, whereas that of M. remotus is broader, flatter, and narrowed just at the apex. The apex of the median lobe bears a simple dorsal process in both species, but that of M. remotus is low and rounded (in apical view; Fig. 2D ) and that of M. ephemeralis is more strongly elevated and subquadrate ( Fig. 2C ). The median armature is quite different in the two, with the arms of M. remotus thin, acute, and slightly dorsally curved ( Figs. 2E–F ). The arms of M. ephemeralis are more nearly triangular, straighter along the leading edge, and straight to subserrate along the trailing edge, with the apices less strongly pointed ( Figs. 2A–B ).

Description. PEL= 3.80–5.17 mm; PNW= 2.68– 3.24 mm. Body oblong oval; frons ( Fig. 1A ) minutely punctate; frontal stria not too strongly impressed, sinuate at middle. Prothorax ( Fig. 1C ) with sides convergent, arcuate; pronotum with a single lateral stria, continuous with anterior marginal, not or barely meeting anterior apices of lateral marginal striae behind the eyes; pronotum with strong punctures mediad lateral stria in posterior two-thirds, punctate area about as wide or slightly wider than area between lateral stria and lateral pronotal margin; few additional larger punctures present on each side at front behind meeting point of anterior and marginal striae. Prosternum with anterior lobe evenly rounded to slightly truncate at front, marginal stria complete, with slightly denser punctures at sides; prosternal keel with striae variable, from present in less than basal half to nearly complete; lateral margin of anterior tibiae subarcuate, with 7–8 marginal spines, their teeth moderately well developed. Elytra ( Fig. 1B ) with outer subhumeral stria nearly complete, abbreviated just slightly at base, striae 1–3 complete, stria 4 complete or slightly abbreviated at base; stria 5 present in apical half or less, may be nearly absent, sutural stria weakly impressed in apical half or less. Mesosternum about 2.25 times as wide as long, evenly emarginate at front, with complete marginal stria lined with punctures; mesometasternal stria complete along anterior margin, discontinuous from lateral metasternal stria in front of metacoxae; meso- and metasternal disks with only fine ground punctures at middle, with coarser punctures at sides. Propygidium ( Fig. 1D ) rather sparsely punctate, with small punctures separated by their widths or slightly more; pygidial punctures somewhat smaller, but about as dense; both with conspicuous ground punctation and transverse waves of fine microsculpture.

Male median lobe ( Figs. 2A–C ) with thin, outwardly arcuate proximal apodemes slightly over one-third total length of median lobe; distal portion of median lobe swollen beneath median armature, narrow but flattened in most of apical half, then dorsoventrally expanded at gonopore; apex of median lobe bearing simple, laminate dorsal process, slightly reclinate, nearly equal in height to gonopore, subquadrate dorsally; median armature borne on curving basal plate, winglike, subtriangular in shape, with straight leading edge and slightly arcuate, serrate trailing edge.

Remarks. Margarinotus remotus has traditionally been put in the subgenus Paralister Bickhardt on the basis of the single pronotal stria, and on those simple grounds this species is placed there as well. However, beyond this character it is not clear that they belong here, and Wenzel (unpublished) proposed a subgenus solely for M. remotus . Should this prove justified in more comprehensive studies, then the present species should accompany it. Some specimens of the type series were collected directly from the burrow entrances of California ground squirrels ( Spermophilus beecheyi [Richardson]). The species are likely to be obligate inquilines of these burrows. The specimens collected from ‘vernal pool’ were floating, alive, on the surface of recently flooded areas where they were presumably flooded out of burrows. The type locality is in the Santa Ynez Valley of southern California, and one of the paratypes is from the Santa Monica Mountains ( Fig. 3 ).

Figures

Fig. 1. Margarinotus ephemeralis. A. Frons, anterior view. B. Elytron, dorsal view. C. Pronotum, dorsal view. D. Pygidium, posterodorsal view.

Fig. 2. Margarinotus ephemeralis and Margarinotus remotus, median lobe of aedeagus. A. M. ephemeralis, dorsal view.B.M. ephemeralis, lateral view.C. M. ephemeralis, apical view of gonopore. D. M. remotus, apical view of gonopore. E. M. remotus, dorsal view. F. M. remotus, lateral view.

Fig. 3. Map of known California localities for Margarinotus spp.