Diagnosis and Phylogenetic Relationships of the Monotypic Genus Stetholiodes (Coleoptera: Leiodidae)1 Quentin D

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BRIEF NOTE DIAGNOSIS AND PHYLOGENETIC RELATIONSHIPS OF THE MONOTYPIC GENUS STETHOLIODES (COLEOPTERA: LEIODIDAE)1 QUENTIN D. WHEELER,2 Department of Entomology, Ohio State University, Columbus OH 43210 OHIO J. SCI. 81(4): 165, 1981

Seventy years have passed since the tube attached to a Wild M-3 dissecting only known specimen of Stetholiodes microscope and a Wild M-12 compound laticollis was discovered by Blatchley in microscope. northeastern Indiana and described by Fall (see Blatchley 1910, Fall 1910). No Taxonomic Considerations While a number of sound diagnostic additional specimens have been collected, 1 and the relationships of this curious characters of 5 . laticollis and a lengthly beetle to other North American Leiodinae description of the species given by Fall (Leiodidae) has remained obscure. Both (1910) make its redescription presently Blatchley and Fall were initially im- superfluous, it would be useful to add pressed by an apparent similarity of this to the diagnosis and to include characters beetle to species of the genus Leiodes of the aedeagus previously unexamined. (referred to at that time as "Anisotoma"), A new and enlarged description will be but upon further study concluded that called for if and when the species is actual relationships were with Anisotoma rediscovered. (then called "Liodes"). After examining the holotype, I believe that my predeces- Stetholiodes laticollis Fall sors were misled by symplesiomorphic Stetholiodes laticollis Fall, 1910:4; characters and that certain synapo- Blatchley, 1910:288; Wheeler, 1979a: morphic characters support placement 261. of this beetle in or near Agathidium. Type locality: USA, Indiana, Steuben The purpose of this note is to briefly County (May 25, 1909). reconsider this intriguing species, includ- Type depository: Museum of Compara- ing a description of the male genitalia, tive Zoology, Harvard University, in and to discuss my opinions in regard to H.C. Fall Collection. the natural relationships of Stetholiodes Diagnostic combination—Body form to other North American leiodid beetles. elongate-oval (fig. 4); elytra with 9 com- The holotype was borrowed from the plete, punctate interneurs (terminology Museum of Comparative Zoology, Har- of Erwin 1974); mesosternum nearly vard University. The specimen was horizontal (not elevated-laminiform); relaxed in Barber's fluid, studied in a antennal club consists of abruptly en- deep-depression slide by compound micro- larged segments IX, X, and XI (fig. 1), scopy, and remounted. The aedeagus was segment VII is larger than VIII but dissected out, studied, and is presently smaller than apical three; pronotum stored in a microvial of glycerin attached broad (fig. 5); postocular tempora not to the pin of the specimen. Dissection well-developed (fig. 3); apical segment and general methods follow those cited of maxillary palpus acicular (fig. 2); previously (Wheeler 1979a, 1979b). aedeagus (figs. 6-8) with median lobe Drawings were prepared with a drawing- (ml) narrowed at apex, ventral piece (vp) deeply emarginate medially, para- xManuscript received 24 April 1980 and in meres (p) sinuate near apex, endophallus revised form 20 August 1980 (#80-21). 2Present address: Department of Entomol- (en) with medial spine (ms) and a pair ogy, Cornell University, Ithaca NY 14853. of small, serrate sclerites (ss). 165 166 QUENTIN D. WHEELER Vol. 81

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FIGURES 1-8. Steiholiod.es laticollis: fig. 1, antenna; fig. 2, apex maxillary palpus; fig. 3, lateral margin of head (ventral view); fig. 4, habitus (dorsal view); fig. 5, right half pronotum (dorsal view); fig. 6, apex of median lobe (ventral view); fig. 7, apex of paramere (lateral view); fig. 8, aedeagus (lateral view). Drawings not to scale. Ohio J. Sci. THE GENUS STETHOLIODES 167

Relationships of Stetholiodes ventral piece, parameres, and small Until a broad cladistic analysis is endophallic armature], but firm synapo- completed for the genera of Leiodinae, morphies cannot yet be recognized. or at least Agathidiini, a detailed account Maxillary palpus.—Acicular segments of inter-generic relationships is problem- of the maxillary palpus do occur else- atical because data concerning character where, in Agathidium (e.g., A. sp. from polarities are lacking. Nonetheless, an Malaysia). examination of the characters previously Elytral interneurs.—The presence of 9 used in evaluations of the relationships complete, punctate elytral interneurs is of Sletholiodes indicates that they were plesiomorphic. They are known in vari- symplesiomorphies and therefore ineffec- ous genera of the subfamily (Wheeler tual. I have made a cursory look at 1979a), and their occurrence in both several characters and made inferrences Stetholiodes and Anisotoma is symplesio- about their polarities among Stetholiodes morphic. and related genera (i.e., Anisotoma and Postocular tempora.—Many Agathidium Agathidium). I have previously specu- beetles have well-developed postocular lated on ties between Stetholiodes and tempora (e.g., fig. 2 in Wheeler 1977), Agathidium (Wheeler 1979a, p. 261), and which are interpreted as apomorphic. expand upon the supportive apomorphic They are absent in some other Agathidium characters below. species (e.g., A. sexslrialum), in all Antennae.—Structure of the antennae Anisoloma beetles, and in Stetholiodes; of Stetholiodes has caused some confusion. this absence is therefore symplesio- Descriptions of the antennae indicate morphic. that segment VII is larger than VIII In my paper on Anisotoma (Wheeler (Fall 1910, Blatchley 1910), and thus 1979a), I indicated in error that Stetho- the genus is usually keyed-out as having liodes has well-developed postocular tem- a 5-segmented club (Brown 1971, Hatch pora. The character linking Stetholiodes 1929). The structure of the antennae to Agathidium that I should have cited (fig. 1), however, is very similar to that was the 3-segmented antennal club. of some species of Agathidium (e.g., Based on these structural considera- A. depressum, see Fall 1934). I would tions, I suggest that Stetholiodes is (subjectively) interpret the club as being closely related to Agathidium, and, in 3-segmented (an apparent apomorphy fact, could be synonymous with that for the genus Agathidium) since antennal genus. In particular, the small endo- segments IX, X, and XI are very phallic armature, curvature of the abruptly enlarged, and are distinctly parameres, and abrupt enlargement of larger than VII. Although VII is larger the apical three antennal segments sup- than VIII, it is not inordinately so for port this conclusion. If we ignore plesio- Agathidium. morphic structures of the head (absence Aedeagus.—Judgements about polarity of well-developed postocular tempora) of aedeagal structures are particularly and elytra (punctate interneurs) that hard to make because no broad surveys resemble conditions found in Anisotoma, of these have been made, although Stetholiodes does look very much like Hlisnikovsky (1964) does illustrate the some species of Agathidium having a genitalia of many species. It is likely broadly ovate body-form and punctate that some of the noted modifications are elytra (e.g., A. depressum and related of less than generic significance. species). Curvature of the parameres does not frequently occur in the genus Anisoloma Ecological Relationships (Wheeler 1979a) and can reasonably be Very little is known about the biology regarded as apomorphic where it occurs of Stetholiodes. Blatchley (1910) col- in Agathidium and in Stetholiodes. There lected the type specimen from Sphagnum seems to be a basic phenetic similarity moss in northern Indiana. Many in the types of modifications found in Agathidium (adults and larvae) are Stetholiodes to those seen in certain known to be associated with various Agathidium [shapes of median lobe, slime-molds (Myxomycetes) and fungi 168 QUENTIN D. WHEELER Vol. 81

(Benick 1952, Russel 1979), and it would LITERATURE CITED seem reasonable to search for Stetho- Benick, L. 1952 Pilzkafer und kaferpilze. Acta Zool. Fenn. 70: 1-250. liodes in similar situations. Blatchley, W. S. 1910 An illustrated de- Because no evidence presently indi- scriptive catalogue of the Coleoptera or beetles (exclusive of the Rhyncophora) known cates a sister-group relationship between to occur in Indiana. Nature Publ., In- Stetholiodes and some subunit of Agathi- dianapolis. dium, it would be unwarranted to Brown, W. J. 1971 Leiodidae. In: Arnett, synonymize these genera now (e.g., R. H., Jr. * The beetles of the United States sister-group relationship of these taxa at (rpt. ed.). American Entomological Insti- tute, Ann Arbor. the generic level cannot be ruled out; Erwin, T. L. 1974 Studies of the sub tribe although intuitively it seems unlikely). Tachyina (Coleoptera: Carabidae: Bembi- My analysis emphasizes the apparent diini), Part II: A revision of the New World- relationship of Stetholiodes with species Australian genus Pericompsus LeConte. Smithson. Contr. Zool., no. 162. of Agathidium (particularly A. depressum Fall, H. C. 1910 New Silphidae of the tribe and related species), and should help Anisotomini. Canadian Entomol. 42: 4-8. in identification of any additional speci- 1934 A review of the North American mens that might be collected. More species of Agathidium (Coleoptera: Silphidae). Entomol. Amer. 14: 99-131. detailed analyses of ecology, structure, Hatch, M. H. 1929 The genera and subgenera and relationships will be possible only of Leiodidae and Clambidae. J. N. Y. when more specimens are discovered, Entomol. Soc. 37: 1-6. and future studies of Agathidium beetles Hlisnikovsky, J. 1964 Monographische bear- beitung der gattung Agathidium Panzer should include a consideration of Stetho- (Coleoptera). Acta Entomol. Mus. Nat. liodes in an effort to further refine our Prague, Suppl. no. 5, pp. 3-239. understanding of its relationships. Russel, L. K. 1979 Beetles associated with slime molds (Mycetozoa) in Oregon and Acknowledgments. This paper was made pos- California (Coleoptera: Leiodidae, Sphin- sible by a Presidential Fellowship from Ohio didae, Lathridiidae). Pan-Pac. Entomol. State Univ. awarded in support of a project en- 55: 1-9. titled "Comparative morphology, cladistics Wheeler, Q. D. 1977 Placement of Anisotoma and a revised classification of the genera of fenderi Hatch (Coleoptera: Leiodidae: Aga- Lymexylidae (Coleoptera)." Dr. Alfred F. thidiini). Entomol. News 88: 137-138. Newton, Jr. generously loaned the holotype 1979a Slime mold beetles of the genus specimen and extended his hospitality during Anisotoma (Leiodidae): classification and several visits to the Museum of Comparative evolution. Syst. Entomol. 4: 251-309. Zoology. Ginter Ekis, Mike Glorioso, Steve 1979b Revision and cladistics of the Nichols, Charles Triplehorn, and Larry Middle American genus Creagrophorus Mat- Watrous read and commented on various drafts thews (Coleoptera: Leiodidae). Quaest. En- of the paper. tomol. 15: 447-479.