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.