Ptychognathus riedelii (A. Milne-Edwards, 1868 )

Lagare, Nickel Jean S., Mapi-Ot, Emmarie F., Molina, Ziljih S., Neri, Jemateo B., Nuñeza, Olga M. & Mendoza, Jose Christopher E., 2020, On a collection of freshwater and estuarine crabs (Crustacea: Brachyura) from Mindanao Island, the Philippines, Zootaxa 4868 (3), pp. 301-330 : 315

Ptychognathus riedelii (A. Milne-Edwards, 1868)

Fig. 5C

Ptychognathus riedelii, Ward 1941: 2 .

Material examined. 10 males, 28.1 by 25.4 mm—29.9 by 26.1 mm ( ZRC; NJL160503–12 ), Layawan River, Brgy. Toliyok, Oroquieta town , Misamis Occidental prov., coll. N.J. Lagare, 16 Sep. 2016 ; 3 males, 19.5 by 17.5 mm—20.1 by 18.5 mm ( ZRC; NJL160834–36 ), Brgy. Dalipuga , Iligan town, Lanao del Norte prov., coll. N.J. Lagare, 19 Sep. 2016 ; 7 males, 13.9 by 12.5 mm—19.9 by 18.9 mm, 13 females, 14.8 by 13.7 mm—20.1 by 17.3 mm ( ZRC; NJL160901–20 ) Brgy. Tagbalogo, Naawan town , Misamis Oriental prov., coll. N.J. Lagare, 12 Sep. 2016 ; 1 male, 25.1 by 22.1 mm ( ZRC; NJL182540 ) Brgy. Tikulon, Malita town, Davao Occidental prov. , coll. N.J. Lagare, 18 & 19 Oct. 2018 ; 3 males, 17.7 by 16 mm—21.1 by 18.4 mm, 2 females, 16.5 by 14.5 mm, 15.7 by 14.1 mm, Don Marcelino town, Davao Occidental prov. , coll. E.F. Mapi-ot, 2018 .

Remarks. Ptychognathus riedelii (A. Milne-Edwards, 1868) (type locality: Sulawesi, Indonesia) is widely distributed within the islands of Indonesia ( Flores, Sumatra, and Halmahera), as well as in the Andaman Is. ( Holthuis 1978; Cai & Ng 2001). In the Philippines, P. riedelii has been reported from the Davao Gulf by Ward (1941). The present specimens agree well with the description and illustrations provided by Cai & Ng (2001: 686, fig. 16), and this species is now known to be locally common in northern and southern Mindanao as well (see Table 1). The specimens were collected in small freshwater rivers & streams at depths of less than 1 m, among stones and pebbles in the substrate.

Figures

FIGURE 5. Colour photos of recently preserved crabs (dorsal habitus). A, Ptychognathus altimanus (Rathbun, 1914), male 21.1 by 19.9 mm (ZRC), Tagoloan, Misamis Oriental; B, Ptychognathus pusillus Heller, 1865, male, 13.1 by 10.7 mm (ZRC), Tagoloan, Misamis Oriental; C, Ptychognathus riedellii (A. Milne-Edwards, 1868), male, 28.9 by 25.0 mm (ZRC), Oroquieta, Misamis Occidental; D, Pyxidognathus granulosus A. Milne-Edwards, 1879, female, 15.4 by 17.3 mm (ZRC), Maigo, Lanao del Norte; E, Utica gracilipes Adams & White, 1848, male, 24.2 by 22.8 mm (ZRC), Iligan, Lanao del Norte; F, Varuna litterata (Fabricius, 1798), male, 42.1 by 37.5 mm (ZRC), Dapitan, Zamboanga del Norte.G, Austruca perplexa (H. Milne Edwards, 1852), male, 13.9 by 10.6 mm (ZRC), Tagoloan, Misamis Oriental; H, Ocypode ceratophthalmus (Pallas, 1772), male, 30.8 by 27.8 mm (ZRC), Manukan, Zamboanga del Norte. Scale bars: 10 mm.