Custotychus watrousi Chandler and Geromini, 1962

Chandler, Donald S. & Geromini, Sarah D., 1962, A Revision of the Eastern Nearctic GenusCustotychusPark and Wagner, 1962 (Coleoptera: Staphylinidae: Pselaphinae), The Coleopterists Bulletin 1962 (2), pp. 217-242 : 217-242

9. Custotychus watrousi Chandler and Geromini , new species

( Figs. 10 , 23a–b , 31 , 34 )

Specimens Examined. n = 70: Holotype male: //MO: St. Louis Co . 1 mi. SE Pacific , 38.4718°N, 90.7212°W, 26-VI-2005, damp debris in drainage ditch L.E. Watrous / [red label] HOLOTYPE Custotychus watrousi Chandler & Geromini // ( FMNH) . Paratypes: Illinois: La Salle Co.: VI-21- 1952 (1M 3F, FMNH) . Mississippi: Oktibbeha Co.: Noxubee National Wildlife Refuge , III-11-1981, G.L. Snodgrass, hardwood litter, (1M 1F, MEMC) ; same locality, III-25-2008, J.A. MacGown & J.G. Hill, litter at base of Quercus species in upland hardwood forest (1M, MEMC) . Missouri: Harrison Co .: 7 mi. NW Ridgeway , X-27-1978, D.S. Chandler, sift forest litter (2M, DSCC) . Jefferson Co.: Pacific Palisades Cons[ervation] Area , II-9-2015, L.E. Watrous, leaf litter (6M 2F, UNHC) . St. Louis Co .: 1 mi. SE Pacific , VI-26-2005, L.E. Watrous, damp debris in drainage ditch (2M, UNHC) . 1.1 mi. SE Pacific , VII-15-2007, L.E. Watrous, litter & soil (3M 3F, UNHC) . 1.4 mi. E Pacific , V-16-2007, L.E. Watrous, bottomland soil (1M, UNHC) . 1.4 mi. E Pacific , V-16-2007, L.E. Watrous, rotten logs (2M 3F, UNHC) . 1.5 mi. E Pacific , IV-11-2008, L.E. Watrous, under bark (5M 12F, UNHC; M 1 F, LSAM) . 2 mi. SE Pacific , XI-4-2005, L.E. Watrous, bottomland leaf litter (3M 3F, UNHC) . 3 mi. E Pacific , V-29-2007, L.E. Watrous, soil wash (3M 1F, UNHC) . Ohio: Champaign Co.: Cedar Bog , X-19-1974, D.S. Chandler, hardwood

forest area (3F, DSCC), young silver maple area (1M 3F, DSCC). Vinton Co.: Lake Hope , XI-2- 1974, D.S. Chandler (1M, DSCC) .

Description. Body: Brown to dark brown, sometimes with abdomen darker than remainder of body; 1.58–1.68 mm long. Male: Eyes with about 40 facets. Metasternal tubercle preapical ( Fig. 23a, b ), apex positioned at about 3/4 point of metasternal length; in lateral view, tubercle erect, apex obliquely subtruncate, sometimes nearly acute, anterior margin of apex higher, posterior face concave; in posterior view, preapically expanded, minimum stem width about 1/2 width of preapex; tubercle height 0.039 mm, maximum width preapex 0.037 mm, minimum stem width 0.021 mm [tubercle measurements based on specimen from 3 mi. NE Pacific, MO; UNHC]. Mesotibiae with preapical spur aciculate, apical spur broad with 2 distant teeth at apex. Ventrite 2 slightly concave in middle third ( Fig. 31 ); ventrite 6 with small indistinct circular impression at middle through length. Aedeagus ( Fig. 10 ) 0.32 mm long; in dorsal view, median lobe elongate with subparallel lateral margins, with slight preapical narrowing to broadly subtruncate apex, lateral arms curving, somewhat swollen, with long apical tooth, shorter ventral tooth barely visible medially, area between arms membranous with longitudinal wrinkles; in lateral view, lateral arms broadening to apex, apex roughly emarginate, apical margin coarsely serrate with large tooth at both dorsal and ventral margins; parameres swollen in apical fourth. Female: Eyes with 18–30 facets; lacking mesotibial spurs.

Collection Data Synopsis. Collections were made from February to July and October to November. The species appears to be associated with hardwood forest litter, with about a third of the specimens extracted from rotten logs or from under bark. Specimens are present in the following collections: DSCC, FMNH, LSAM, MEMC, and UNHC.

Distribution. Custotychus watrousi occurs from southern Ohio to central Missouri and Mississippi ( Fig. 34 ). Individuals were seen from the following states: IL, MS, MO, and OH.

Etymology. This species is named for Larry E. Watrous, who provided most of the Missouri specimens of this species, as well as many specimens of other species and genera from this poorly collected state.

Comments. This species, C. leei , and C. natchez are the most commonly taken species of the upper Mississippi drainage. The females cannot be separated other than by association with the males, but the males are easily separated by the impression on ventrite 2 of C. watrousi and C. leei , while this ventrite is smoothly convex in C. natchez . The metasternal tubercle is shorter for C. watrousi , slightly higher than wide, while for C. leei the tubercle is nearly twice as high as wide. This distinction can be subtle, but the male genitalia lead to ready separation based on the form of the lateral arms of the dorsal plate in lateral view.

Figures

Figs. 8–15. Custotychus species, dorsal and left lateral view of aedeagus. 8) C. cavei; 9) C. verticalis; 10) C. watrousi;

Figs. 16–27. Custotychus species, scanning electron micrographs right lateral (a) and posterior (b) views of metasternal tubercle. 16) C. chickasaw; 17) C. daggyi; 18) C. lobatus; 19) C. turnbowi; 20) C. rothorum; 21) C. spinosus; 22) C. verticalis; 23) C. watrousi; 24) C. carloritaorum; 25) C. leei; 26) C. minor; 27) C. natchez. Grid for measurements of 20 or 50m at bottom of micrographs.

Figs. 28–32. Custotychus species. 28) C. pocahontas, scanning electron micrographs of right lateral (a) and posterior (b) views of metasternal tubercle. Grid for measurements of 20 or 50m at bottom of micrographs; 29) C. carloritaorum, mesotibial spurs; 30) C. spinosus, mesotibial spurs; 31) C. watrousi, abdominal ventrites, ventrolateral view; 32) C. daggyi, right maxillary palpus, ventral view. Scale bar = 0.1 mm.

Figs. 34–36. Distribution of Custotychus species. 34) Distribution of species in the spinosus and verticalis species-groups: C. rothorum and C. spinosus, and C. cavei, C. verticalis, and C. watrousi; 35) Distribution of C. minor; 36) Distribution of other species in the minor species-group: C. carloritaorum, C. leei, C. natchez, and C. pocahontas.