Periophthalmus pusing, Jaafar & Polgar & Zamroni, 2016

Jaafar, Zeehan, Polgar, Gianluca & Zamroni, Yuliadi, 2016, Description of a new species of Periophthalmus (Teleostei: Gobiidae) from the Lesser Sunda Islands, Raffles Bulletin of Zoology 64, pp. 278-283 : 279-283

Periophthalmus pusing sp. nov.

( Figs 1 , 2 , Tables 1, 2)

Materials examined. Holotype: MZB 23015, female, 35.3 mm SL, Indonesia, Sumba , Waingapu, Kawangu,

collected by Jaafar Z. and Zamroni Y., 10 November 2012. Paratypes (n=14): AMS I.46780-001, male (32.8 mm SL) and 2 females (33.2–36.6 mm SL), collection data same as holotype ; RMNH. PISC.38420, male (29.7 mm SL), 2 females (30.1–32.8 mm SL), collection data same as holotype ; USNM 432497 , male (29.6 mm SL), 3 females (29.6–36.6 mm SL), collection data same as holotype ; ZRC 54416, 2 males (33.0– 36.8 mm SL), 2 females (33.8–37.2 mm SL), collection data same as holotype .

Diagnosis. Adult Periophthalmus pusing sp. nov. are distinguished from all congeners with the following suite of characters: pelvic frenum absent; pelvic fins separate for the entire length; a black spot posteriorly on first dorsal fin, spot usually between ninth and the ultimate spine; first dorsal fin taller than second dorsal fin; interdorsal distance less than half the length of the first dorsal-fin spine. First dorsal-fin elements XI–XV; second dorsal-fin elements I, 10–I, 12; anal-fin elements I, 10–I, 12; pectoral-fin elements 10–12; longitudinal scale rows 42–54; predorsal midline 14–19.

Description. Table 1 shows the morphometric and meristic data for the holotype (MZB 23015). A frequency table with meristic counts for Periophthalmus pusing sp. nov. and P. gracilis is presented in Table 2. The holotype was fixed in formalin and maintained in ethanol (see Fig. 1 ). Fig. 2 is a photograph of a live specimen of Periophthalmus pusing sp. nov. while Fig. 3 is a photograph of a live specimen of P. gracilis . The descriptions below provide details of adult specimens over 30 mm SL. As with other congeners, juvenile specimens, especially those equal or less than 25 mm SL, are difficult to discern to species.

General description: A slender-bodied Periophthalmus with compressed trunk and large, cylindrical head. One row of teeth in both upper and lower jaws; teeth caninoid, evenly spaced; no recurved canine teeth internal to lower jaw symphysis; tongue adnate. Trunk fully covered with scales, scales increase in size posteriorly; opercle and dorsal portion of preopercle with small embedded scales; scales absent on interorbital, isthmus, and snout. First dorsal fin tall, and somewhat rounded; first dorsal fin taller than second dorsal fin, up to two times the height of the second dorsal fin; first dorsal-fin elements almost reaching the second dorsal fin when adpressed; first and second dorsal fins closely set, distance between fins less than half the first spine length of the first dorsal fin. Pelvic frenum absent, pelvic fins separate throughout their length, no basal membrane joining innermost pelvic-fin rays; pelvic fins opaque beige, with light brown scattered pigment on the dorsal area.

Live colouration: Ground colour of live specimens greenishbrown to tan-brown dorsally, silvery white to light beige ventrally. Multiple silvery-white vertical lines on the trunk from the pectoral-fin base to the caudal peduncle; lines more prominent ventrally, almost indiscernible dorsally. Seven to eight dark brown saddle-like bars crossing dorsum as described below. First dorsal fin with distal silvery-white to hyaline band; a broad, submarginal dark brown or black band, posterior section intense brown to black, and appears as a spot; black spot aligns with third saddle-like bar on trunk ( Fig. 2 ); proximal to submarginal band with variable colouration, from greenish yellow anteriorly and reddishorange posteriorly, with two or three rows of bright yellow elongate to circular spots, to entirely reddish orange with one to two rows of hyaline spots. Second dorsal fin with distal hyaline band, with a broad submarginal reddish-orange and, another hyaline band, and a basal dusky reddish-brown band proximally; basal band with one to two rows of small circular dull yellow to hyaline spots. Anal fin hyaline; pectoral-fin membranes hyaline and dusky light green to brown along fin elements; caudal fin hyaline with aligned series of dark brown spots on interradial membranes, appearing as irregular seven to nine dull yellow-brown thin vertical bars; pelvic fins beige, with light subtle light yellow pigmentation on the dorsal area.

Colour in preservative: Ground colour of body beige to dusky brown, creamy beige ventrally; colour most intense anteriorly, dark brown around eyes and on snout. Seven to eight dark brown irregular saddle-like bars crossing dorsum; bars course anteroventrally in the following anterior to posterior pattern: immediately anterior to first dorsal fin, at mid-base of first dorsal fin, just anterior to first dorsal-fin terminus, immediately posterior to origin of second dorsal fin, mid-base of second dorsal fin, immediately posterior to the second dorsal fin, mid-caudal peduncle, posteriormost reach of caudal peduncle. First dorsal fin with thin, distal hyaline band; a broad, submarginal dark brown or black band, posterior section of the band intense brown to black, especially between the ultimate 4-5 spines that appears as a spot in the posterior portion of the first dorsal fin; spot aligns with third saddle-like bar on trunk; proximal to submarginal band, light to dusky brown anteriorly and white to hyaline posteriorly; white elongate spots in two to three rows on spines, especially anteriorly. Second dorsal fin with thin, distal hyaline band, with a broad submarginal brown band and another hyaline band, and a basal dusky brown band proximally; basal band with one to two rows of small circular spots especially on fin elements. Anal fin hyaline; pectoral-fin membranes hyaline and dusky light brown along fin elements; caudal fin hyaline with aligned series of dark brown speckles on interradial membranes, appearing as seven to nine irregular dusky brown thin vertical bars.

Etymology. The specific epithet ‘pusing’, meaning ‘giddy’ in Indonesian, is the common name used by the coastal people of the Lesser Sunda Islands to refer to Periophthalmus mudskippers. These fishes are known as ‘Ikan Pusing’ (Indonesian: ikan=fish, pusing=giddy), as it is believed that consuming these fishes causes headaches and giddiness.

Distribution. Presently known to occur only on the island of Sumba, Indonesia ( Fig. 4 ).

Field notes: The general locality in which this mudskipper was found—Kawangu—is a tide-dominated coastal system with relatively low wave action. Within the mangrove forest, P. pusing sp. nov. was found in a variety of microhabitat types in seaward and higher mangrove areas as well as within, and on sloping banks of tidal creeks. This species was syntopic with two congeners: Periophthalmus argentilineatus and Periophthalmus malaccensis .

Remarks. Adult Periophthalmus pusing sp. nov. differ from all other congeners, except P. gracilis , in the absence of the pelvic frenum, pelvic fin not unified, and the presence of a black spot on the posterior first dorsal fin. Adult Periophthalmus pusing sp. nov. can be differentiated from adult P. gracilis in having XI–XV spines in the first dorsal fin (vs. VI–XII in P. gracilis ), first dorsal fin taller than second dorsal fin (first dorsal fin shorter or equal in height to second dorsal fin in P. gracilis ), interdorsal distance less than half the length of the first dorsal-fin spine (interdorsal distance approximates the length of the first dorsal-fin spine in P. gracilis ). Whereas juvenile specimens (approx. 25–30 mm SL) of Periophthalmus pusing sp. nov. and those of P. gracilis are superficially similar, differences are apparent upon scrutiny. For specimens of the same size, the first dorsal fin in Periophthalmus pusing sp. nov. has more spines, is taller, and has a shorter interdorsal-fin distance. It is extremely difficult to identify the species of most Periophthalmus specimens below 25 mm SL.

Comparative material. Periophthalmus gracilis: USNM 278295, Vanikoro, Solomon Islands, female (42.1 mm SL); USNM 341322 , Solomon Islands, male (36.3 mm SL) ; USNM 278473 , Marieveles , Philippines, male (35.8 mm SL), female (35.5 mm SL); AMS I.22700–014, Daintree River mouth, Australia, 2 females (38.3–40.6 mm SL); AMS I.26333-003, Queensland, Australia, male (39.3 mm SL), 3 females (33.1–39.6 mm SL); AMS I.19355–022, Balikpapan, East Kalimantan, Indonesia, 2 males (20.4–33.0 mm SL), female (33.1 mm SL) ; ZRC 50771, Tritih , Cilacap, Java, Indonesia, 3 females (39.4–46.0 mm SL) ; USNM 366711 , Temburong River , Brunei, 3 males (32.4–34.4 mm SL), female (35.0 mm SL), juvenile (26.7 mm SL) ; ZRC 27057, St. John’s Island , Singapore, 2 males (34.1–34.3 mm SL) ; ZRC 53201, Pandan Mangroves , Singapore, male (34.1 mm SL), 2 females (32.9–35.8 mm SL) ; ZRC 37792, Sarawak, East Malaysia, male (34.5 mm SL), 6 females (33.2–38.3 mm SL) ; ZRC 47563, Pantai Batu Hitam , Pahang, Peninsular Malaysia, female (39.8 mm SL) .

Figures

Fig. 1. Holotype of Periophthalmus pusing sp. nov. MZB 23015, female, 35.3 mm SL, collected in Sumba Island, Indonesia (Photograph by: Sandra Raredon).

Fig. 2. Live specimen of Periophthalmus pusing sp. nov., approximately 35 mm SL, collected in Sumba Island, Indonesia.

Fig. 3. Live specimen of Periophthalmus gracilis, approximately 48 mm SL, collected in Vietnam (Photograph by: Tran Dac Dinh).

Fig. 4. Occurrence of Periophthalmus pusing represented by a black circle—Sumba Island, Indonesia. The base map is courtesy of d-maps. com.