Margarinotus, MARSEUL, 1853

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 : 2-3

KEY TO THE SPECIES OF MARGARINOTUS

KNOWN OR SUSPECTED (†) TO OCCUR IN CALIFORNIA

1. Pronotum with 2 lateral striae, the outer sometimes strongly abbreviated............................4

1′. Pronotum with a single lateral stria.............2

2. Outer subhumeral elytral stria present only in basal half, obsolete posteriorly ....................... .......... Margarinotus obscurus (Kugelann) †

2′. Outer subhumeral elytral stria complete......3

3. Pronotum with dense, discrete cluster of punctures behind anterior margin on each side ( Fig. 1C ); median armature of aedeagus with dorsal/proximal margin rough to serrate, straight ( Figs. 2A–B ) ..................................... ............... Margarinotus ephemeralis n. sp.

3′. Pronotum with only sparse, minute ground punctation behind anterior margin; median armature of aedeagus thin, smooth along dorsal/ proximal margin, curved dorsad ( Figs. 2D–E ) ............... Margarinotus remotus (LeConte)

4. Elytra with all dorsal striae complete, stria 5 and sutural stria nearly connected at base ( Fig. 7B )..... Margarinotus thomomysi n. sp.

4′. Elytra with at least fifth, usually fourth, and sometimes additional striae strongly abbreviated.............................................................5

5. Pronotum with outer lateral stria <3/4 complete............................................................... 6

5′. Pronotum with outer lateral stria>3/4, usually fully, complete..............................................7

6. Apex of median lobe of aedeagus with two distinct teeth, these widely separated, with weak or absent median tooth ( Figs. 5C–D ); lateral pronotal stria usually between 1/2 and 2/3 complete......... Margarinotus umbilicatus (Casey)

6′. Apex of median lobe with 3 teeth, the median tooth most prominent ( Fig. 5E ); lateral pronotal stria usually <1/2 complete................................ .................... Margarinotus umbrosus (Casey)

7. Entire dorsal surface finely but distinctly punctate; lateral pronotal striae close together........... Margarinotus harrisii (Kirby)

7′. Dorsal surface with only minute and extremely sparse ground punctation, punctures not visible at low magnification; lateral pronotal striae variable.......................................................... 8

8. Size large (> 7 mm); sutural and fifth dorsal elytral striae strongly abbreviated, frequently absent; outer lateral pronotal stria very close to marginal stria, sometimes joined with it anteriorly ..... Margarinotus sexstriatus (LeConte)

8′. Size smaller (usually <7 mm); sutural stria never absent, usually present in apical 1/3 or more; lateral pronotal stria usually distant from margin, never joined with it..........................9

9. Frontal stria usually interrupted at middle, sometimes completely obsolete; prosternal striae usually absent; inner subhumeral stria often vaguely indicated by discontinuous series of punctures in apical half of elytra................. ................ Margarinotus fractifrons (Casey)

9′. Frontal stria usually compete; prosternal striae present or absent; inner subhumeral stria not indicated ......................................................10

10. Side of pronotum relatively flat, inner lateral stria strongly impressed and sinuate in basal half, closely approaching outer stria at base; pygidial punctures relatively large and umbilicate; apparently only synanthropic (in CA).. Margarinotus merdarius (Hoffmann)

10′. Side of pronotum continuously convex with middle, the inner stria not as strongly impressed, though variably sinuate, approaching the outer stria at the base or not; pygidial punctures smaller ................................................11

11. Fourth elytral stria abbreviated at base, usually present only in apical two-thirds; elytron transversely impressed across apex between striae 2 and 4; pronotum with more conspicuous discal punctures along inner lateral stria ...... Margarinotus pluto (Casey)

11′. Fourth elytral stria complete or only barely abbreviated at base; elytron not transversely impressed apically; pronotal punctation not becoming more conspicuous near inner lateral stria................. Margarinotus rectus (Casey)

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. 7. Margarinotus thomomysi. A. Frons, anterior view. B. Elytron, dorsal view. C. Pronotum, dorsal view. D. Pygidium, posterodorsal view.

Fig. 5. Margarinotus umbilicatus and Margarinotus umbrosus, median lobe of aedeagus. A. M. umbilicatus, dorsal view. B. M. umbilicatus, lateral view. C. M. umbilicatus, apical view of gonopore (variant). D. M. umbilicatus (typical form), apical view of gonopore. E. M. umbrosus, apical view of gonopore. F. M. umbrosus, dorsal view. G. M. umbrosus, lateral view.