Lucasioides gracilentus Li & Wang, 2024

Wang, Jin, Yao, Chong-Hui, Jiang, Chao & Li, Wei-Chun, 2024, Integrative taxonomy reveals exceptional species diversity of Lucasioides from China (Isopoda: Oniscidea: Agnaridae), Arthropod Systematics & amp; Phylogeny 82, pp. 527-549 : 527-549

3.3. 6. Lucasioides gracilentus Li & Wang sp. nov.

Figures 6 H , 12

Type material.

Holotype. CHINA • 1 ♂; Fujian Province, Putian City, Hugong Mountain ; 25.3490 ° N, 119.0077 ° E, el. 462 m a. s. l.; 4. vii. 2021; X. G. Zeng, J. Wang leg. (DNA no. HGS 2104 , Prep. slide no. L 21060 ) . — Paratypes. • 5 ♂♂, 3 ♀♀, same data as the holotype (DNA nos. HGS 2105 - HGS 2112 ) .

Diagnosis.

Pereonite 1 nearly straight on posterior margin of epimeron, postero-lateral corner convex; pleopod 1 exopod concave at posterior apex and formed two broad lobes, inner lobe longer and broader than outer lobe.

Description.

Body length of males 4.8-5.0 mm, of females 6.0-8.0 mm. Color in alcohol blackish brown, dorsum granulated, bearing irregular white muscle spots (Fig. 6 H ). Pereonite 1 nearly straight on posterior margin of epimeron, postero-lateral corner convex. Noduli laterales on pereonites 2-4 farthest from lateral margin, noduli laterales on pereonites 1 and 7 slightly closer to lateral margin, and noduli laterales on pereonites 5-6 closest to lateral margin (Fig. 12 A ). Telson triangular, width about twice as long as length, lateral margin slightly concave, apex blunted; uropod exopodite about two and half as long as basipodite (Figs 6 H and 12 A ). — Cephalon with arched median lobe, median lobe much longer than lateral lobes (Figs 6 H and 12 A ). Antennula with several aesthetascs on distal tip of third article. Antennal flagellum with second segment two and half as long as first one (Fig. 12 B ). — Pereopod 1 with brush of long setae on carpus and merus (Fig. 12 C ). Pereopod 7 ischium without deep depression on rostral surface, carpus unexpanded on dorsal margin (Fig. 12 D ). — Pleopods 1-5 exopods with Protracheoniscus - type pseudotrachea (Fig. 12 E-I ). — MALE: pleopod 1 exopod concave at posterior tip and formed two broad lobes, inner lobe longer and broader than outer lobe, endopod with broad basal part, narrowed towards beak-shaped posterior tip (Fig. 12 E ); pleopod 2 endopod styliform, nearly as long as exopodite (Fig. 12 F ).

Etymology.

Latin “ gracilentus ” = slender. The new species name refers to the slender habitus of the specimens.

Remarks.

The new species is also inconsistent within Lucasioides if we recognized it by using the morphological traits alone. However, all the mounted structures of this species support it to be assigned as Lucasioides member. Furthermore, the phylogenetic relationship between this species and the other Lucasioides species is well-supported (Fig. 5 ).

The new species is similar to L. boninshimensis ( Nunomura, 1987) in having the convex postero-lateral corner of pereonite 1. But it can be distinguished by the pleopod 1 exopod with inner lobe broader than outer lobe, endopod with a beak-shaped posterior tip (Fig. 12 E ). In L. boninshimensis , the pleopod 1 exopod with inner as wide as outer lobe, endopod with a straight posterior tip ( Nunomura 1987: fig. 115 I).

Figures

Figure 5. Bayesian Consensus tree based on four-gene (COI + 18 S + 28 S + NaK) sequences. Asterisks and circles represent high node support with Bayesian posterior probabilities > 0.95 and maximum bootstrap values > 95. Coloured bars represent hypothesised species groupings.

Figure 6. Habitus of male Lucasioides species in dorsal view. A L. dissectus sp. nov.; B L. isseli (Arcangeli, 1927); C L. dianensis sp. nov.; D L. digitatus sp. nov.; E L. schmidti sp. nov.; F L. nudus Li, 2017; G L. formosus sp. nov.; H L. gracilentus sp. nov.; I L. subcurvatus sp. nov. (Scale: 1 mm).

Figure 12. Lucasioides gracilentus sp. nov. A Holotype in dorsal view; B antenna; C pereopod 1; D pereopod 7; E pleopod 1; F pleopod 2; G pleopod 3 exopod; H pleopod 4 exopod; I pleopod 5 exopod.