Mongoloniscus crenatus Jiang, Li & Huang, 2024

Jiang, Chao, Zhong, Jing, Wang, Zhidong, Li, Weichun & Huang, Luqi, 2024, Taxonomic study on the genus Mongoloniscus Verhoeff, 1930 (Isopoda, Agnaridae) from China: morphological and phylogenetic analyses, ZooKeys 1202, pp. 229-253 : 229-253

Mongoloniscus crenatus Jiang, Li & Huang sp. nov.

Figs 4 A, B , 5 , 6

Type material.

Holotype. China: ♂ ( 20210417001 ), Sichuan Province, Baoxing County, Muping Town, Lengmugou Provincial Geological Park (30.3699 ° N, 102.8125 ° E), 1020 m asl., 14. iv. 2021, coll. Chao Jiang.

Paratypes. China: 3 ♂♂, 8 ♀♀ ( 20210417002 – 20210417012 ), same data as the holotype . 4 ♂♂, 6 ♀♀ ( 20210412063 – 20210412066 ), Hubei Province, Yichang, Xiaoxita Forestry Park (30.7853 ° N, 111.3180 ° E), 100 m asl., 12. iv. 2021, coll. Zhidong Wang & Tianyun Chen . 1 ♂ ( 20210512006 ), Shaanxi Province, Zhashui County, Lengbinggou Village (33.6931 ° N, 109.0239 ° E), 1020 m asl., 12. x. 2021, coll. Chao Jiang . 3 ♂♂, 1 ♀ ( 20210417016 – 20210417019 ), Sichuan Province, Baoxing County, Dengchigou (30.5341 ° N, 102.9410 ° E), 1810 m asl., 17. iv. 2021, coll. Chao Jiang ; 3 ♂♂, 1 ♀ ( 20210416040 – 20210416043 ), Qionglai, Datong Village , Dalong Road (30.5042 ° N, 103.3063 ° E), 770 m als., 14. iv. 2021, coll. Chao Jiang ; 5 ♂♂, 24 ♀♀ ( 120220827008 – 20220827025 ), Hanyuan County, Fuling Town, Hanyuan Service Area (29.4370 ° N, 102.6343 ° E), 1080 m asl., 27. viii. 2022, coll. Chao Jiang ; 6 ♂♂, 9 ♀♀ ( 20220828036 – 20220828048 ), Tianquan County, Binhe Park (30.0584 ° N, 102.7597 ° E), 760 m asl., 28. viii. 2022, coll. Chao Jiang ; 18 ♂♂, 23 ♀♀ ( 20220829013 – 20220829028 ), Wenchuan County, Yingxiu Town (31.0557 ° N, 103.4887 ° E), 880 m asl., 29. viii. 2022, coll. Chao Jiang .

Diagnosis.

Cephalon with median lobe convex, medially with a small incision. Antennal flagellum with distal article twice as long as proximal article. Noduli laterales almost at same distance from the lateral margins. Pereopod 6 basis and pereopod 7 ischium fringed with long setae. Pleopod 1 exopod deeply bilobed at apex, inner lobe much longer than outer lobe; apex of male pleopod 1 endopod bent outwards and pointed.

Description.

Body length of males 7–9 mm and females 8–11 mm. Body elongated and convex, ~ 2–2.5 × as long as widest pereonite. Dorsum distinctly granulated, brown-gray color with usual yellowish muscle spots. Numerous gland pores along entire pereonite margin. Pereonite 1 with rounded postero-lateral corner, posterior margin nearly straight. Noduli laterales almost at the same distance from lateral margins (Fig. 4 A, B ). Telson triangular, approximately twice as wide as long, lateral margins slightly concave at distal one third, posterior apex blunted; uropodal exopod ~ 2–2.5 and 1.5–2 × as long as protopod in males and females, respectively; protopod with an incision on outer margin (Figs 4 A, B , 5 B ).

Cephalon with rounded lateral lobe no evidence surpasses eyes, median lobe convex, medially with a small incision (Fig. 5 A ). Eyes with 15–19 ommatidia. Antenna with fifth article of peduncle longer than flagellum; flagellum with distal article 1.6–2.1 × as long as proximal one (Fig. 5 C ).

Pereopod 1 bearing brush of long setae on its carpus and merus (Fig. 5 D ). Pereopod 6 basis fringed with long setae and a distal protrusion on sternal margin (Fig. 5 E ). Pereopod 7 ischium with sternal margin slightly concave and fringed with setae, rostral surface with shallow depression; carpus slightly expanded on the tergal margin (Fig. 5 F ).

Pleopods 1–5 exopods with monospiracular internal lungs (Fig. 5 G – K ). Male: pleopod 1 exopod oval, with robust sinuous outer margin; apex deeply bilobed and bearing several setae, inner lobe much longer than outer lobe (Fig. 5 G ). Pleopod 2 exopod nearly triangular, bearing one line of setae on the outer margin (Fig. 4 H ). Pleopod 1 endopod with broad basal part, narrowed towards apex, apex bent outwards and pointed (Fig. 5 G ); pleopod 2 endopod longer than exopod, distal article thin and long (Fig. 5 H ).

Remarks.

The new species resembles M. koreanus in morphology. It can be distinguished from the latter by the cephalon median lobe medially with a small incision, pereopod 7 with an unexpanded carpus on the tergal margin, and pleopod 1 endopod with a pointed distal apex. In M. koreanus , the cephalon median lobe is medially continuous, pereopod 7 has an expanded carpus on the tergal margin, and the distal apex of the pleopod 1 endopod is blunted. Furthermore, this species and M. koreanus formed two clades with high support in the phylogenetic analysis (Fig. 2 ), and their interspecific distances were much higher than their intraspecies distances (Suppl. material 1: table S 2).

Etymology.

Latin crenatus = notched. The new species name refers to the anterior margin of the cephalon with a small notch in the middle. We suggest the Chinese common name as “ 刻痕蒙潮虫 ”.

Distribution.

China (Hubei, Shaanxi, Sichuan).

Figures

Figure 2. Maximum likelihood phylogenetic tree based on combined COI and 28 S data for Mongoloniscus. Values above the branches represent the posterior probability (PP) and bootstrap support (BS), BS < 70 % or PP < 0.9 are indicated as hyphens.

Figure 4. Habitus of Mongoloniscus species A, C, E, G male, holotype B, D, F, H female, paratype A, B M. crenatus sp. nov. C, D M. polyacanthum sp. nov. E, F M. parvus sp. nov. G, H M. orientalis sp. nov. The blue circles show the noduli laterales arrangement. Scale bars: 3 mm.

Figure 5. Mongoloniscus crenatus sp. nov., holotype A cephalon, pereonites 1 and 2 in dorsal view B pleonites, telson and uropod in dorsal view C second antenna D pereopod 1 E pereopod 6 F pereopod 7 G pleopod 1 H pleopod 2 I – K pleopods 3–5 exopods. Scale bars: 1 mm.

Figure 6. Mongoloniscus polyacanthum sp. nov., holotype A cephalon and pereonite 1 in dorsal view B pleonites, telson, and uropod in dorsal view C second antenna D pereopod 1 E pereopod 6 F pereopod 7 G pleopod 1 H pleopod 2 I – K pleopods 3–5 exopods. The abrupt tip of pleopod 2 endopod are indicated as dotted lines. Scale bars: 1 mm (A – F); 0.5 mm (G – K).