Cyclorhipidion xeniolum | Southeast Asian Ambrosia Beetle ID

Taxonomic history

Cyclorhipidion xeniolum Smith, Beaver & Cognato 2020 (in Smith et al. 2020bSmith et al. 2020b:
Smith SM, Beaver RA, and Cognato AI. 2020b. A monograph of the Xyleborini (Coleoptera, Curculionidae, Scolytinae) of the Indochinese Peninsula (except Malaysia) and China. ZooKeys 983: 1-442. https://doi.org/10.3897/zookeys.983.52630): 205.

Diagnosis

1.65−1.8 mm long (mean = 1.71 mm; n = 5); 3.09−3.4 times as long as wide. This species is distinguished by the short, obliquely truncateobliquely truncate:
nearly truncate but rounded not flat in lateral view
and flat declivitydeclivity:
downward slope of either the pronotum or elytra
that is approximately 25% of total elytralelytral:
pertaining to the elytra
length, armed with large tuberclestubercle:
a small knob-like or rounded protuberance of the exoskeleton
on interstriaeinterstria:
longitudinal spaces along the elytra between the striae, which is not as<br /> impressed and bear smaller punctures.
1 and 3; interstriaeinterstria:
longitudinal spaces along the elytra between the striae, which is not as<br /> impressed and bear smaller punctures.
2 always unarmed; posterolateralposterolateral:
relating to end of the side part/portion
margins rounded; declivitaldeclivital:
pertaining to the elytral declivity
interstriae 1 and 2 setaeseta:
small hair-like or scale-like structure
uniseriate.

May be confused with

This species most closely resembles C. bodoanum, C. californicum, C. cognatoi Lin and Smith, 2022, and C. nemesis.

This species is a part of the challenging C. pelliculosum species group. Species in the group are most easily distinguished by the rows of setaeseta:
small hair-like or scale-like structure
along declivitaldeclivital:
pertaining to the elytral declivity
interstriae 1and 2. See table below:

species	declivital declivital: pertaining to the elytral declivity interstriae 1 setaeseta: small hair-like or scale-like structure rows	declivital declivital: pertaining to the elytral declivity interstriae 2 setaeseta: small hair-like or scale-like structure rows	total body length (mm)	total body length/width ratio	lateral lateral: pertaining to the side profile of elytralelytral: pertaining to the elytra declivity	interstriae 2 granules	interstriae 1 & 3 granules
C. achlys Smith, Beaver, and Cognato, 2022	3	1	3.4	3.09	steeply rounded	absent	present
C. beaveri Lin and Smith, 2022	1	1	1.68−1.85	2.91−3.05	steeply rounded	present	present
C. bodoanum	2	1	1.6−2.4	2.5−3.29	steeply rounded	absent	present
C. californicum	2	2	2.2	3.14	steeply rounded	absent	present
C. cognatoi Lin and Smith, 2022	2	1	2.95−3.28	2.82−2.93	steeply rounded	absent	present
C. distinguendum	3	2	2.5−3.11	2.6−3.0	steeply rounded	absent	present
C. inarmatum	2	1	2.75−3.0	2.75−3.0	steeply rounded	absent	present
C. nemesis	1	1	2−2.2	2.75−3.07	steeply rounded	absent	present
C. pelliculosum	3	1	3.2−3.5	2.67−3.0	steeply rounded	rare, on basalbase: point or edge closest to the body; opposite of apex 1/4	present
C. taedulum Smith, Beaver, and Cognato, 2022	2	1	2.7	3	steeply rounded	absent	present
C. tenuigraphum	2	2	2.7−3.0	2.5−3.0	steeply rounded	Often on apicalapex: point or edge furthest from the body; opposite of base 1/3	present
C. triste	2	1	2.92−3.47	2.78	steeply rounded	absent	absent
C. xeniolum	1	1	1.65−1.8	3.09−3.4	obliquely truncateobliquely truncate: nearly truncate but rounded not flat in lateral view	absent	present

Distribution

China (Yunnan), Thailand

Host plants

known only from Castanopsis sp. (Fagaceae) (Smith et al. 2020bSmith et al. 2020b:
Smith SM, Beaver RA, and Cognato AI. 2020b. A monograph of the Xyleborini (Coleoptera, Curculionidae, Scolytinae) of the Indochinese Peninsula (except Malaysia) and China. ZooKeys 983: 1-442. https://doi.org/10.3897/zookeys.983.52630)

DNA data

specimens not available for sequencing