Acanthopotamon fungosum ( Alcock, 1909 )

Mitra, Santanu & Pati, Sameer Kumar, 2021, A new species of freshwater crab, Teretamon kapota sp. nov. (Decapoda: Brachyura: Potamidae) and a new record from Arunachal Pradesh, North-Eastern India, Records of the Zoological Survey of India 121 (1), pp. 1-9 : 6

Acanthopotamon fungosum ( Alcock, 1909)

1909. Potamon (Paratelphusa) fungosum Alcock, Rec. Indian Mus. , 3 (3): 250.

2019. Acathopotamon fungosum : Pati and Thackeray, Zootaxa, 4440 (1): 9.

Material examined: 1♂ (CW 21.6 mm, CL 16.6 mm, CH 9.6 mm, FW 7.6 mm), Arunachal Pradesh, East Siang district, small hill stream connected to Sibyia River, near Siluk village , ca. 30 km north east of Pasighat (28.175°N, 95.470°E), altitude 336 mASL, 4-xi-2019, coll. S. Mitra ( ZSI-C. 8252/2) .

Material compared: Acathopotamon fungosum : Lectotype ♂ ( ZSIK 6611-6624 /9), India: Assam, Cachar, Darband pass, coll. J. Wood-Mason ; Paralectotype 1 ♂ and 1 ♀ ( ZSIC 6611-6624 /9), data same as Lectotype ; 1 ♂ and 2 ♀ ( ZSIC 5540 /10), India: Assam, Cachar, coll. E.B. Baker.

Diagnosis: Carapace sub-hexagonal, slightly broader than long, convex, covered by short spongy fur, carapace dorsal surface broadly corrugated and lumpy, much pitted when denuded; cervical groove only demarcated in mesogastric area, otherwise its superficial; epigastric cristae broad, blunt; well advance of postorbital cristae; post orbital cristae short, not confluent with first epibranchial tooth; external orbital tooth broadly triangular; anterolateral margin gently convex, with 4 epibranchial teeth, first epibranchial tooth broadly triangular, rests are sharp ( Figure 8A ); third maxilliped ischium elongately rectangular with distinct longitudinal median sulcus; exopod not distally tapered, with well developed flagellum, longer than merus width; carpus and merus of cheliped with distinct subdistal and subterminal spine; ambulatory legs covered with short and long velvety setae; suture between thoracic sternites 2 and 3 distinct, eighth thoracic sternites possesses a transverse ridge at the suture between thoracic sternites 7 and 8 interrupting the longitudinal median line; Sterno-pleonal cavity reaching imaginary line joining beyond the anterior edge of cheliped bases; male pleon broadly triangular; G1 terminal article outwardly curved, long, slender, sub cylindrical, tapering towards tip, covered by short setae ( Figure 8B, C ); G2 distal part is distinctly longer than half of the basal part ( Figure 8 D ); female vulvae located on the middle of 6 th sternites, opening large, longitudinally oval.

Distribution: INDIA: Arunachal Pradesh (Present record), Assam and Mizoram ( Pati et al., 2019).

Remarks: Acanthopotamon fungosum was descried from Cachar, Assam ( Alcock, 1909), having a patchy distribution range in Northeast India. Shallow streams or a Rocky River bed is the suitable habitat for this species. The present report forms its first record from Arunachal Pradesh and extension of its distributional range further northeast.

Figures

Figure 8. Acanthopotamon fungosum (Alcock, 1909) (21.6 × 16.6 mm) (ZSIK-C. 8252/2): A. Overall dorsal view; B. Dorsal view of left G1; C. Ventral view of left G1; D. Left G2.