Cedraderus, Leschen & Gimmel, 2023

Leschen, Richard A. B. & Gimmel, Matthew L., 2023, Cedraderus, a new genus for “ Xylophilus ” constrictus Fall (Coleoptera: Tenebrionoidea: Aderidae), Zootaxa 5239 (2), pp. 296-300 : 297-299

Cedraderus , new genus

( Figs. 1–10 )

Type species. Xylophilus constrictus Fall 1901: 259 , here designated.

Diagnosis. Cedraderus is easily distinguished from other aderid genera based on the relatively soft body with uniseriate vestiture ( Fig. 3 ), pronotum with deep subapical and antebasal sulci ( Fig. 2 , arrows), presence of a supraepipleural groove on the elytron, the absence of a metafemoral brush in both sexes, and the linear, unlobed mesotarsus with non-nodiform tarsomere 4. The genus appears most similar to the Austral genus Scraptogetus ( Alekseev & Grzymala 2015; Grzymala & Leschen 2020) with which it shares a complete suture separating abdominal ventrites 1 and 2 ( Fig. 5 , arrow), but differs from it by the aforementioned characters.

Description. Total length 1.53–1.88 mm. Body ( Figs. 8–10 ) moderately convex. Dorsal vestiture uniseriate, each seta arising anteriad of primary puncture ( Fig. 3 ). Head strongly inclined; not strongly constricted posteriorly, temples absent; head in males distinctly wider than width of pronotum, in female slightly wider than pronotum. Transverse occipital ridge absent. Eyes protuberant, coarsely faceted, entire to weakly anteriorly emarginate; dimorphic, with male eyes much larger, frons about 0.9 times width of single eye in frontal view in male and about 2.5 times width of eye in female; interfacetal setae absent. Antennal insertion not produced on integumental ridge; antennomeres ( Fig. 1 ) sexually dimorphic, longer and more filiform in males than females. Frons flat, lacking lateral sulci. Frontoclypeal suture present. Maxillary palpomere 4 triangular to securiform. Pronotum ( Fig. 2 ) transverse, 0.65–0.70 times as long as wide (not sexually dimorphic), anterior and posterior angles not produced, width greater than length, sides rounded, anterior margin straight, posterior margin weakly curved, basal margin wider than apical margin; disc with deep transverse sulci posteriad of anterior margin and anteriad of posterior margin ( Fig. 2 , arrows), visible in lateral view, paired fovea and impressions absent. Prosternum in front of coxae at midline equal to, or slightly longer than, procoxal cavity; prosternal process short and incomplete, apex acute. Notosternal sutures absent. Procoxal cavities slightly transverse and narrowly separated. Scutellar shield not abruptly elevated anteriorly, apically rounded. Elytra about 1.8–2.2 times as long as combined width in males, 1.6–1.9 times as long as combined width in females; elytra 4.7–5.0 times as long as pronotum in males, 4.5–4.7 times as long as pronotum in females; epipleuron absent but elytron laterally ( Fig. 9 ) with a supraepipleural groove present along entire length and extending to apical one-fifth along elytral suture. Mesoventrite ( Fig. 4 ) with procoxal rests, intercoxal process narrow, lacking anterior notch; suture between mesoventrite and mesanepisternum distinct. Mesocoxal cavities narrowly separated. Mesometaventral junction simple, lacking interlocking mechanism. Metaventrite without deep punctures; metathoracic discrimen distinct, long; exposed portion of metanepisternum long. Metendosternite with long lateral arms; anterior processes absent; laminae present, well-developed. Hind wing without radial cell; medial field consisting of 2 free veins. Metacoxae narrowly separated. Legs lacking sexual dimorphism, metafemora lacking setal brush in both sexes; protarsus slightly shorter than protibia, T1 shorter than T2 + T3, T4 slightly shorter than one-half the length of T3 and one-third the length of T5; mesotarsus slightly shorter than mesotibia, T1 = T2 + T3, T4 slightly less than one-half length of T3, T5 subequal to T3 + T4; metatarsus about as long as metatibia, T1 = T2 + T5, T2 longer than T3, T3 shorter than T2 and T4; tarsomeres very weakly lobed; empodial setae absent. Abdominal ventrites of equal lengths; intercoxal process acute; complete suture separating ventrites 1 and 2 ( Fig. 5 , arrow), externally distinctly furrowed laterally and present as a line at middle, internally demarcated as a carina at the sides, positioned anterior to the external furrow; ventrite 5 of female unmodified. Aedeagus ( Figs. 6, 7 ) with phallobase and apicale distinctly indicated; phallobase posteriorly obtusely pointed; apicale with alae (proximal extensions) curved inward, well-developed accessory lobes present, each with three short setae along the shaft and one long apical seta; penis about as long as tegmen, with short, asymmetrical anterior struts, apex acute. Female with spiculum ventrale forked at base and about as long as abdominal ventrites 4 and 5 combined; spermatheca narrow, long and sinuate, expanded at base and arising from bursa. Ovipositor moderately long; coxites subdivided with disticoxite pigmented and separated from basicoxite by an oblique suture, about one-fifth length of entire coxite, with mediodistal projection; styli distally placed, articulated to coxites.

Etymology. The generic name is derived from a combination of the Latin cedrus , meaning juniper, referring to the only recorded microhabitat data for the genus, and the generic name Aderus .

Distribution. United States (Arizona [ Chandler 2002], California [ Fall 1901; Chandler 2002]).

Specimens examined. USA: ARIZONA: Yavapai Co. (1). CALIFORNIA: Kern Co. (22); Los Angeles Co. (4); Mono Co. (2); Riverside Co. (14); Tulare Co. (1); San Bernardino Co. (19); San Luis Obispo Co. (3); Ventura Co. (19) (ASUHIC, NZAC, SBMNH).

Included species. Cedraderus constrictus (Fall, 1910) , new combination.

Comments on classification. Xylophilus constrictus was described by Fall (1901: 259) based on Californian specimens collected in the Sierra Madre in Los Angeles County and around Lake Tahoe. Fall (1901) remarked on the peculiarity of the pronotum having a transverse sulcus just behind the head and a shallower sulcus along the basal margin. He did not place this species into any of Casey’s (1895) American aderid genera. Leng (1920) listed X. constrictus questionably under Axylophilus Casey , but this genus differs from Cedraderus by the diagnostic characters above, including complete lack of pronotal sulci and complete fusion of ventrites 1 and 2 and lack of a suture.

The current classifications established by Báguena-Corella (1948, 1962) and Werner (1990) for regional faunas require critical revision ( Lawrence & Ślipiński 2010). Werner (1990) divided Nearctic Aderidae into two unnamed subfamilies based on the presence or absence of accessory lobes (referred to as “parameres”), Subfamily I and Subfamily II, respectively. Cedraderus has been proposed as a relative of Scraptogetus and Cnopus based on unpublished molecular data ( Alekseev & Grzymala 2015; Grzymala and Leschen 2020), and all three have the accessory lobes present. Furthermore, Werner (1990) proposed two unnamed tribes within each subfamily, and within Subfamily I, based on the absence and presence of setal brushes on the metafemora in both sexes, Scraptogetus and Cedraderus would be placed separately (brushes are present in Scraptogetus ). Phylogenetic relationships between Scraptogetus and Cedraderus and their relationships to other Aderidae are confounded by symplesiomorphies, which includes the metendosternite with well-developed laminae and a complete suture between abdominal ventrites 1 and 2, a character that is present in Eocene and Mesozoic fossils ( Alekseev & Grzymala 2015; Bao et al. 2020). On the other hand, potential features defining family groups, such as the loss of accessory lobes and the presence of metafemoral brushes, will have to be critically examined for the family as a whole, because some of these characteristics, like the presence/absence of accessory lobes in Werner’s (1990) classification, and the form of vestiture in Báguena-Corella’s (1962) classification, can be polymorphic within a genus ( Israelson 1971).

Accounting for the most recent work by Gompel (2017, 2022), the North American fauna of Aderidae consists of 11 described genera and 50 species. The key to the North American genera provided by Chandler (2002), which did not account for X. constrictus , is revised as follows:

1. Pronotum with a transverse antebasal sulcus or deep impression............................................... 1a

- Pronotum without a transverse antebasal sulcus or deep impression; an impression, if present, is shallow and not distinct laterally............................................................... 2 [remainder of key in Chandler 2002]

1a. Pronotum with deep subapical and antebasal sulci extending to lateral margin; head with frontoclypeal suture; metafemur lacking setal brush; abdominal ventrites 1 and 2 connate but separated by a complete suture....... Cedraderus , new genus

- Pronotum with a deep depression in posterior one-third, punctiform laterally; head without frontoclypeal suture; metafemur with setal brush; abdominal ventrites 1 and 2 completely fused and lacking a suture.................. Cnopus Champion

Variation. Cedraderus constrictus is a variable species which is found from Northern California (Trinity and Plumas Counties, https://bugguide.net/node/view/492693) southward to Los Angeles County, then eastward to Arizona in Yavapai County . The overall color varies from dark to light brown, usually with the head dark brown to black and the underparts darker, and rarely entirely unicolorous brown. The shape of maxillary palpomere 4 varies from widely triangular to securiform, and within a series the shape varies between males and females (Kern and San Luis Obispo counties) or are similar (Riverside and Ventura counties). The sexes are dimorphic, with the male eyes larger and elytra being longer and narrower than those of females. The shape of the male antenna is more slender than in the female, and in most specimens antennomeres 3–7 are conical and more or less equal in length to antennomere 11, with antennomeres 8 and 9 distinctly shorter. A unicolorous dark brown specimen from San Luis Obispo County (SBMNH) has antennomeres 3–11 elongate and subcylindrical in shape. Specimens from Riverside County all seem to fall between this variation, and the Lake Tahoe syntype has antennomeres 7–10 slightly shorter than the specimens we have examined (https://mczbase.mcz.harvard.edu/guid/MCZ:Ent:24336). A more detailed study of this variation may reveal a complex of species.

Biology. Virtually nothing is known about the natural history of this species. Most specimens were collected in July without habitat data, though a few specimens were collected at lights, including one from Plumas Co. posted on BugGuide (https://bugguide.net/node/view/2028842). One dissected female from San Bernardino Co. had a gut containing undifferentiated matter. A series of five specimens was collected from Juniperus californica Carr. (Cupressaceae) during early June ( USA: Riverside Co., along CA- 74 in Piñon Flats, 33.58295°,–116.45486°, 1230 m, 6 June 2015, ex Juniperus californica, M. Gimmel & L. Indruchová ), and two specimens were collected from Quercus (Fagaceae) (1, USA: CA: Los Angeles Co., near Grassy Hollow Visitor Center, 34.37363°,–117.71875°, 2230 m, 22 July 2017, M. & L. Gimmel, ML222; 1, USA: CA: Los Angeles Co., along Big Pines Road, 34.42311°,– 117.80209° 1450 m, 19 June 2018, M. Gimmel & R. Kundrata, ML292) (all specimens deposited in SBMNH).

Figures

FIGURES 1–7. Cedraderus constrictus, male morphological structures. 1) Antenna; 2) Pronotum, dorsal aspect, arrows show subapical and antebasal sulci; 3) Setation of elytral disc; 4) Mesoventrite with mesanepisterna; 5) Abdominal ventrites 1 and 2 (arrow shows suture separating the two ventrites). Aedeagus: 6) Dorsal aspect; 7) Ventral aspect. Scale bar (for Figs. 6 and 7) = 0.10 mm.

FIGURES 8–10. Cedraderus constrictus, habitus of specimens from UC James Reserve, Riverside Co., CA. Male (SBMNHENT0055168): 8) Dorsal aspect; 9) Lateral aspect. 10) Female (SBMNHENT0054966), dorsal aspect. Scale bar = 1.0 mm.