Lathrobium (Lathrobioma) divisum LeConte, 1880

Haberski, Adam & Caterino, Michael S., 2024, A review of Nearctic Lathrobium (Coleoptera, Staphylinidae), with revision and descriptions of new flightless species from the mountains of the southeastern U. S., ZooKeys 1198, pp. 193-277 : 193

Lathrobium (Lathrobioma) divisum LeConte, 1880

Lathrobium divisum LeConte, 1880: 176.

Lathrobium franciscanum Casey, 1905: 84. New synonym.

Type material.

Lectotype, Lathrobium divisum LeConte, herein designated (MCZ): "Vanc. / [handwritten] L. divisum Lec. / COLLECTION / TYPE [handwritten] Lathrobium divisum / [red] Type 6453 / Lectotype Lathrobium divisum LeConte Desg. Haberski & Caterino." Lectotype, Lathrobium franciscanum Casey, herein designated (USNM): "LosGatos CAL/ CASEY bequest 1925 / [handwritten] Los Gatos is in Santa Clara Co. not far from Sta. Cruz California / [red] TYPE USNM 38114 / Lectotype Lathrobium franciscanum Casey Desg. Haberski & Caterino."

Other material.

USA: California: Santa Clara Co.: Los Gatos (1, USNM); Mendocino Co. : Gualala (1, USNM) ; Illinois (1, MCZ).

Diagnosis.

This species can be distinguished from other Lathrobioma by its large size. Additionally, males are the only Lathrobioma to lack an emargination on sternite VIII and have an asymmetrical aedeagus. Females have paraprocts subequal in length to the basal portion of tergite IX, while other species have paraprocts that are short or fully divided.

Description.

Large species, body length 7-8 mm. Body coloration red, elytra bicolored, appendages lighter yellow. Gular sutures arcuate; antennomeres V-VII as long as wide. Elytra as long as pronotum. Females with paraprocts undivided, apices as long as basal portion; sternite VIII weakly oblong. Male sternite VIII without emargination, thick black setae at apex; genitalia as in Fig. 29 .

Distribution.

Canada: BC. USA: CA, IL, OR, WA ( Newton 2022).

Remarks.

Lathrobium franciscanum is reduced to synonymy with Lathrobium divisum because the distinguishing characters given by Casey (1905) were insufficiently distinctive. Lathrobium franciscanum was described from one female and one male, which were differentiated from L. divisum based on subtle morphological differences in somatic characters. Its body was supposedly "more slender," punctures "somewhat sparser," head "not so large," and prothorax "slightly narrower" than the head as opposed to "much narrower" in L. divisum ( Casey 1905). These differences are difficult to see and fall within the range of intraspecific variation in longer series of other Lathrobium . We examined the genitalia of both species and found no differences in the shape of their aedeagi.

Casey (1905) placed L. divisum in Lathrobium s. str., but after examining the types, we transfer it to Lathrobioma based on the following synapomorphies: metatarsi compact, tarsomeres I-IV subequal in length, each ~ 1/3 as long as fifth tarsomere; maxillary palpomere III more than 0.4 × as wide as long; and male sternite VIII with bristles positioned apically. The final character is presented here for the first time.

Figures

Figures 29 - 34. Lathrobium terminalia A female terminalia B male sternite VIII C aedeagus in ventral view D Aedeagus in lateral view. 29 L. divisum 30 L. nanulum 31 L. othioides 32 L. scolopaceum 33 L. tenue 34 L. amplipenne. Scale bars: 1 mm.