Baixi ant-loving beetle (Apharinodes baixiensis) from Guangdong, the second species found in China after Apharinodes sinensis

NEWS - Baixi ant-loving beetle (Apharinodes baixiensis Zhu & Wang, sp. nov.) from Baixi Provincial Nature Reserve, Heyuan City, Guangdong Province, is the second species in the genus found in China after Apharinodes sinensis Yin & Jiang 2017.

Apharinodes Raffrary 1890 belongs to Hybocephalini (Coleoptera, Staphylinidae, Pselaphinae) which was established for Apharinodes squamosa Raffrary 1890 from Singapore. Then, the second species Apharinodes miranda Raffrary 1895 in Singapore. The third species, Apharinodes papageno Nomura 1989 from Japan and A. sinensis from China.

Apharinodes baixiensis is a beetle with males having a body of 1.77 mm in length, 0.76 mm in width, widest at second visible adbominal tergite. Length of body parts (mm): head (0.38), eye (0.13), antennae (0.73), pronotum (0.37), elytra (0.54); width: head (0.38), eye (0.07), pronotum (0.37), elytra (0.68).

Body dark reddish-brown, mostly covered by thick yellowish setae. Setae on legs and antennomeres 11 finer; on other antennas, slightly stronger; on other body parts, enlarged to squamous scales.

Head subelliptical, as long as wide, widest across eyes. Dorsum entirly covered by yellowish scale-like setae; setae on clypeus slightly thinner. Clypeus slightly convex, nearly covering bases of antennae; eyes large, distinctly prominent, berry-shaped, each composed of about 20 facets; postocular margins shorter than eyes, roundly narrowed towards head base; frons with two connected semi-circular patches of squamous setae; maxillary palpi small and short, three-segmented, with distinct conical palpal cone; gular flat area.

Antennae robust, each with ten antennomeres which are close to each other, large club forming antennomeres 11; antennomere 1 robust, cylindrical, about equal to length of antennomeres 2+3+4 combined; antennomeres 3 to 10 strongly transverse, successively wider, quite close to each other; antennomeres 11 largest, about equal to length of antennomeres 2 to 10 combined, medio-dorsal surface with large, deep, circular excavation, nearly bowl-shaped, width/length = 0.83.

Pronotum width equal to length, subcylindrical, broadest at middle, almost straight from middle to base, narrowed from middle towards apex. Surface fully covered by dense squamous scales, has two lateral pairs of squamous bands of setae and one median longitudinal band, almost equal in length.

Elytra convex, wider than long, posterior margin with band of dense scale-like setae, two basal foveae covered by squamous setae, with weak discal and sutural striae. Metathoracic wings lacking. Mesoventrite densely covered with small squamous setae; metaventrite densely covered with setae at middle, areas posterior to mesocoxae with two longitudinal projections that extend to metaventral posterior margin.

Legs slightly lighter than other parts in color, densely covered by hair-like setae. Inner claw of each tarsus highly degraded into seta shape.

Abdomen subglobose, wider than long; tergite IV as long as V, with pair of lateral foveae, tergites VI and VII slightly shorter than V, tergite VIII sparsely punctured, rather slightly emarginate at posterior margin; sternites IV to VII successively shorter, sternite VIII shallowly emarginate at middle of posterior margin, sternite IX composed of paired membranous structures.

Aedeagus 0.27 mm long, median lobe broad, with large basal capsule, broadly emarginate along apical margin; parameres invisible, probably lacking; endophallus composed of two sclerites in vertical arrangement, dorsal sclerite spina-like, ventral sclerite much stronger, spiral-shaped and slightly curved, more sclerotised laterally.

A. baixiensis can be distinguished from its relatives by the cup-shaped antennomere XI in dorsal view (vs. A. sinensis, generally with a deep and rounded excavation).

Prothorax bears two pairs of lateral squamous bands of setae and one median longitudinal band, nearly equal in length (vs. anterolateral patches of squamous setae on pronotum shorter than basolateral patches).

Inner claw of each tarsus strongly degenerated into a setae (vs. inner claw also degenerated into a setae, but more developed).

Front with two separate semicircular patches of squamous setae; endophallus composed of two sclerites in a vertical arrangement, dorsal sclerite spine-like; ventral sclerite much stronger, spiral and slightly curved, more sclerotized laterally, parameres not visible, may be absent (vs. endophallus composed of three long sclerites, short and thick parameres, each with three thick apical setae).

Original research

Zhu J, Wang C-B (2024). Apharinodes baixiensis sp. nov., a new species from Guangdong, China (Coleoptera, Staphylinidae, Pselaphinae). Biodiversity Data Journal 12: e139609, DOI:10.3897/BDJ.12.e139609

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