Pseudochromis socotraensis, Gill, Anthony C. & Zajonz, Uwe, 2011

Gill, Anthony C. & Zajonz, Uwe, 2011, Pseudochromine and pseudoplesiopine dottyback fishes from the Socotra Archipelago, Indian Ocean, with descriptions of two new species of Pseudochromis Rüppell (Perciformes: Pseudochromidae), Zootaxa 3106, pp. 1-23 : 14-20

Pseudochromis socotraensis sp. nov.

Socotra Dottyback

Figures 10–13 ; Tables 1, 4–5

Holotype. SMF 29200, 62.7 mm SL, Socotra Archipelago, Abd al-Kuri Island, north coast, E of Badh Issa, biotope code 6.5.2, 5– 7 m, U. Zajonz & Plaga, A., 12 April 1999 (ST-211).

Paratypes. SMF 33401 (ex 29200), 3: 33.1–52.4 mm SL, collected with holotype; SMF 29204, 9: 28.6–48.2 mm SL, Socotra Archipelago, Abd al-Kuri Island, E coast, Ras Anjara Bay, narrow fringing reef, 30 m width, 50– 70 m in length, dominated by Acropora intermedia and A. clathrata , very high species richness (biotope code S6.5.2), 3–9 m, U. Zajonz & M. Apel, 8 April 1999 (ST-173/150); SMF 29201, 5: 30.7–40.5 mm SL, Socotra Archipelago, NE coast of Socotra Island, Roosh-Siqarah Protected Area, 12°37’14”N 54°21’05”E, biotope code S6.4.1, 11–17 m, U. Zajonz, 25 March 1999 (ST-106); AMS I.45576-001, 2: 45.2-60.0 mm SL, Socotra Archipelago, Abd al-Kuri Island, SW coast, “Trident Bay”, 12°13’27”N 52°04’16”E, highly diverse assemblages of large massive and encrusting corals, and an associated diverse fish community, 6–15 m, U. Zajonz, F.N. Saeed, M. Apel & E. Zandri, 4 April 2000 (ST-709); BMNH 2011.9.27.1, 1: 47.4 mm SL, collected with AMS I.45576-001; SMF 29226, 3: 45.2–71.0 mm SL, collected with AMS I.45576-001; USNM 402766, 55.5 mm SL, collected with AMS I.45576-001; SMF 29230, 4: 22.5–37.1 mm SL, Socotra Archipelago, NE coast of Darsa Island at anchorage, 12o07'03"N 53o18'18"E, small coral blocks on slightly sloping sand bottom, 27–29 m, U. Zajonz, 8 April 2000 (ST- 723b); SMF 29237, 3: 38.5–51.3 mm SL, Socotra Archipelago, NE coast of Socotra Island, Roosh Protected Area, 12°37’12’’ N 54°21’14’’E, biotope code 6.6.2, 15– 18 m, U. Zajonz & M. Ismail, 14 April 2000 (ST-733); NHCY-P 5 (ex 29237), 10: 26.6-45.0 mm SL, collected with SMF 29237; SMF 33550, 1: 34.5 mm SL, Socotra Archipelago, N coast of Socotra Island, Di Hamri, 12 m, U. Zajonz, H. Pulch & F.N. Saeed, 15 June 2009 (ST 09-02-01); SMF 33551, 1: 49.3 mm SL, Socotra Archipelago, N coast of Socotra Island, Ditimri, 12°37’13”N 54°18’02”E, H. Pulch & F.N. Saeed, 12 December 2009 (ST 09-21-02).

Diagnosis. A species of Pseudochromis with the following combination of characters: dorsal-fin rays III,29– 31; scales in lateral series 41–47; anterior lateral-line scales 29–36; head with two bright blue to turquoise stripes and conspicuous black pigmentation around upper laterosensory pores; body and fins generally dark grey to black.

Description (based on 44 specimens, 22.5–71.0 mm SL; data for all types followed, where variation was noted, by data for holotype in parentheses). Dorsal-fin rays III,29–31 (III,31), last 6–22 (11) segmented rays branched; anal-fin rays III,18–20 (III,19), last 5–16 (15) segmented rays branched; pectoral-fin rays 17–19 (19/19); upper procurrent caudal-fin rays 6–8 (8); lower procurrent caudal-fin rays 6–7 (7); total caudal-fin rays 29–32 (32); scales in lateral series 41–47 (44/44); anterior lateral-line scales 29–36 (32/30); anterior lateral line terminating beneath segmented dorsal-fin ray 16–22 (20/19); posterior lateral-line scales 5–10 + 0–1 (6 + 0/? + 0); scales between lateral lines 3–5 (4/4); horizontal scale rows above anal-fin origin 12–15 + 1 + 2–4 = 15–19 (13 + 1 + 3/13 + 1 + 3); circumpeduncular scales 19–22 (20); predorsal scales 20–25 (22); scales behind eye 3–4 (3); scales to preopercular angle 4–6 (5); gill rakers 4–6 + 11–12 = 15–18 (5 + 12); pseudobranch filaments 7–11 (9); circumorbital pores 15–42 (34/42); preopercular pores 9–24 (21/24); dentary pores 4–5 (4/4); posterior interorbital pores 1–2 (2).

Lower lip incomplete; dorsal and anal fins without scale sheaths, although sometimes with small scales intermittently overlapping fin bases; predorsal scales extending anteriorly to point ranging from posterior AIO to mid AIO pores; opercle with 3–6 weak to relatively distinct serrations; teeth of outer ceratobranchial-1 gill rakers well developed mainly on raker tips only, although often with well-developed teeth running most of length of upper few rakers (particularly in larger specimens); anterior dorsal-fin pterygiophore formula S/S/S + 3/1 + 1/1 + 1*/1/1/1 + 1*, S*/S/S + 3/1 + 1/1/1/1 + 1*/1 or S/S/S + 3/1 + 1/1 + 1/1/1 + 1/1 (S/S/S + 3/1 + 1/1/1 + 1/1/1 + 1); dorsal-fin spines relatively stout and pungent; anterior anal-fin pterygiophore formula 3/1 + 1/1 + 1/1 or 3/1 + 1/1/1 + 1 (3/1 + 1/1/1 + 1); anal-fin spines stout and pungent, second much stouter than third; pelvic-fin spine stout and pungent; second segmented pelvic-fin ray usually longest, sometime subequal to third; caudal fin rounded to truncate or emarginate, often with lower lobe produced; vertebrae 10 + 16; epineurals 17–19 (17); epurals 3.

Upper jaw with 2–6 pairs of curved, enlarged caniniform teeth anteriorly, and 4–5 (at symphysis) to 1–3 (on sides of jaw) inner rows of small conical teeth, outermost of rows of conical teeth much larger and more curved than inner rows; lower jaw with 2–5 pairs of curved, enlarged caniniform teeth anteriorly, and 3–5 (at symphysis) to 1 (on sides of jaw) inner rows of small conical teeth, teeth on middle of jaw larger and curved; vomer with 1–2 rows of small conical teeth, forming chevron; palatine with 2–3 rows of small conical teeth arranged in elongate, suboval patch, anterior part of tooth patch more-or-less contiguous with posterolateral arm of vomerine tooth patch; ectopterygoid edentate; tongue rounded to moderately pointed and edentate.

As percentage of SL (based on 15 specimens, 32.5–62.7 mm SL): Head length 20.9–25.2 (20.9); orbit diameter 6.3–9.2 (6.7); snout length 4.7–6.2 (5.6); fleshy interorbital width 4.7–5.6 (5.1); bony interorbital width 2.8–3.7 (3.0); body width 7.7–10.6 (7.8); snout tip to posterior tip of retroarticular bone 11.8–13.5 (11.8); predorsal length 27.4–31.5 (27.4); prepelvic length 27.3–31.1 (27.3); posterior tip of retroarticular bone to pelvic-fin origin 16.4– 19.5 (16.4); dorsal-fin origin to pelvic-fin origin 21.5–24.3 (23.1); dorsal-fin origin to middle dorsal-fin ray 33.8– 39.5 (38.8); dorsal-fin origin to anal-fin origin 35.7–40.9 (37.0); pelvic-fin origin to anal-fin origin 26.3–35.0 (28.5); middle dorsal-fin ray to dorsal-fin termination 23.5–29.3 (28.5); middle dorsal-fin ray to anal-fin origin 20.7–23.9 (22.0); anal-fin origin to dorsal-fin termination 34.5–39.4 (38.8); anal-fin base length 28.4–35.1 (32.4); dorsal-fin termination to anal-fin termination 12.2–14.3 (13.1); dorsal-fin termination to caudal peduncle dorsal edge 8.1–9.7 (9.7); dorsal-fin termination to caudal peduncle ventral edge 14.4–17.3 (16.3); anal-fin termination to caudal peduncle dorsal edge 15.8–17.8 (16.1); anal-fin termination to caudal peduncle ventral edge 8.7–11.1 (10.4); first dorsal-fin spine 1.5–2.8 (2.1); second dorsal-fin spine 3.5–5.2 (3.5); third dorsal-fin spine 5.6–7.1 (5.6); first segmented dorsal-fin ray 8.9–11.6 (10.0); fourth last segmented dorsal-fin ray 12.5–17.7 (17.7); first anal-fin spine 1.6–2.9 (2.2); second anal-fin spine 3.5–5.7 (4.5); third anal-fin spine 3.7–6.9 (4.6); first segmented anal-fin ray 6.6–9.5 (8.1); fourth last segmented anal-fin ray 11.1–15.5 (12.6); third pectoral-fin ray 10.5–13.5 (10.5); pelvic-fin spine 6.0–8.9 (6.5); second segmented pelvic-fin ray 14.2–16.6 (14.4); caudal-fin length 21.7– 25.2 (23.1).

Live coloration (based on photographs of live and freshly dead specimens—coloration more intense when alive; Figures 11–12 ). Head and body grey-brown to dark grey; black pigmentation surrounding sensory pores of head (including upper infraorbital, posterior otic, posterior preopercular, intertemporal, anterior temporal, lower supratemporal and posttemporal pores); large dark grey to black vertically-elongate spot on opercular flap, with bluish cast and edged posteriorly with gold; branchiostegal membranes grey-brown to dusky grey, usually forming series of 1–3 small dark spots immediately below large dark spot on opercular flap; bright blue to turquoise stripe extending from snout tip above eye and above horizontal portion of anterior lateral line to beneath anterior part of dorsal fin; second bright blue to turquoise stripe extending from middle of lower lip to lower edge of eye or midupper part of preopercle; preopercle, subopercle and opercle (below opercle spot) edged with bright blue to turquoise; lips, lower part of head and breast sometimes bright blue to turquoise; iris reddish brown to bright red with oblique bright blue line above and below pupil; broad wedge of cobalt blue extending beneath basal third of pectoral fin from above pectoral-fin axil to lower abdomen; body scales each with reddish brown centres; all but anterior few scales of anterior lateral line each with prominent black basal spot, these becoming less distinct on posterior part of body; dorsal fin dark grey to black with broad bright blue submarginal stripe along distal third of fin; anterior dorsal-fin rays bright blue to turquoise near base, dark grey on remainder; black spot immediately behind base of each dorsal-fin ray; distal edge of dorsal fin bright blue, edged proximally with reddish brown to bright red; anal fin dark grey to black, sometimes with bright blue spot at base of each ray, with 2–3 rows of reddish brown to red spots; distal edge of anal fin bright blue, edged proximally with reddish brown to bright red; caudal fin dark grey to black; bright blue stripe through outer third of upper part of caudal fin; upper and lower distal margins of fin bright blue, edged distally with hyaline; pectoral fins reddish hyaline; pelvic fins pale blue, inner rays pinkish grey.

Preserved coloration. Similar to live coloration: head and body brown to dark grey-brown; black markings on head and fins remain, becoming dark grey-brown to black, blue and turquoise markings become purplish grey.

Habitat and distribution. Collected mainly from coral dominated communities including biotopes dominated by Millepora , Acropora and Porites . One sample was also made in a mixed soft and hard coral community on large rock boulders. Additional visual records were made in 1999-2000 on similar biotopes, and additional hard coral biotopes dominated by Galaxea , and encrusting and massive Agariciidae , Pectiniidae and Musside, and at the few fringing reef sites. In addition the species was sighted on relict reef or spur and groove with mixed macroalgae and hard coral communities, and on mixed macroalgae and/or sparse hard coral communities on rock platform. With 38 occurrences at 74 fish inventory sites P. s o c o t r a e n s i s is the most common and widespread dottyback species on Socotra Archipelago. Is has been recorded from all main islands of the Archipelago and at all coastal directions; its depth range being 3–29 m and beyond. These observations have been confirmed during recent surveys in 2009 and 2011 (H. Pulch, F.N. Saeed, T. Alpermann, U. Zajonz). Its ecological niche therefore appears to be relatively wide, but which variables actually constitute its ecological preferences are not yet clear.

Comparisons. Pseudochromis socotraensis belongs to a complex of species (hereafter termed the “ Pseudochromis dutoiti -complex”) that includes P. aldabraensis Bauchot-Boutin (in Arnoult et al. 1958) from the Arabian Peninsula and Persian Gulf to Pakistan and Sri Lanka (the type locality, Aldabra, is in error—see Gill 2004), P. dutoiti Smith (1955) from east Africa and P. springeri Lubbock (1975) from the Red Sea. Members of the complex differ from congeners—and form a demonstrably monophyletic clade—in having two bright blue stripes on the head and anterior body. Species within the complex can be mostly identified by live coloration characters (Table 4). Pseudochromis socotraensis differs further from P. springeri in body size (largest observed specimen 71.0 mm vs. 37.5 mm SL), and in having more scales in lateral series, and fewer anterior lateral line scales (Table 5). It also differs from P. aldabraensis in tending to have more scales in lateral series, more anterior lateral-line scales, and more segmented dorsal-fin rays (Table 5), although the latter character varies geographically in P. aldabraensis (see Gill 2004: table 3). The four species in the Pseudochromis dutoiti -complex are also differentiated on the basis of counts of laterosensory pores on the head, which proliferate with growth. Pseudochromis springeri has fewer pores than P. aldabraensis , which in turn has fewer pores than P. socotraensis , and P. dutoiti has the most pores ( Figure 13 ).

Remarks. Putative synapomorphic coloration characters (Table 4) suggest that P. dutoiti , P. s o c o tr a e ns i s and P. springeri form a clade exclusive of P. aldabraensis (synapomorphy: conspicuous black pigmentation surrounding upper laterosensory pores on the head). Relationships within this clade are inconclusive: one character (blue wedge extending under pectoral fin from pectoral-fin axil to pelvic-fin base) suggests a sister relationship between P. s o c o t r a e n s i s and P. dutoiti , while the dark anal fin, caudal-fin and body coloration suggests a sister relationships between P. socotraensis and P. springeri .

Research on the niche ecology and conservation genetics of P. s o c o t r a e n i s is currently underway as part of by a joint project of the second author with H. Pulch of the BiK-F.

Etymology. The specific epithet refers to the known distribution of the species.

Material examined. See above type specimens. Additional (non-type) specimens: AMS I.45576-002, 2 specimens (cleared and stained), Socotra Archipelago, Abd al-Kuri Island, SW coast, “Trident Bay”, 12°13’27”N 52°04’15”E, highly diverse assemblages of large massive and encrusting corals, and an associated diverse fish community, 6–15 m, U. Zajonz, F.N. Saeed, M. Apel & E. Zandri, 4 April 2000 (ST-709); SMF 33402, 19: 21.0– 58.5 mm SL, collected with AMS I.45576-002; SMF 29202, 1 specimen, Socotra Archipelago, W coast of Socotra Island, Shuab Bay, Ras Asfar, 12°39’24”N 53°24’07”E, bedrock with encrusting corals and filter feeders in front of cliff (biotope code S4.2.3), 8–10 m, U. Zajonz & M. Apel, 9 March 1999 (ST-017); AMS I.45577-001, 2 specimens (cleared and stained), Socotra Archipelago, Socotra Island, Ditimri, W of Rhiy di-Adho, 12o37'21"N 54o17'17"E, reef slope with rich coral diversity on rock (biotope S6.9.1), 15–20 m, U. Zajonz & M. Apel, 3 April 1999 (ST-148); SMF 29199, 2 specimens, collected with AMS I.45577-001; SMF 29203, 13: Socotra Archipelago, Semha Island, NW coast, biotope code 6.5.2, 10– 13 m, U. Zajonz, F. Krupp & A. Plaga, 15 April 1999 (ST-267); SMF 29228, 3: Socotra Archipelago, NE coast of Abd al-Kuri Island, 700 m off Bir Al-Agooz, 12°11’40”N 52°19’18”E, coral dominated biotope (biotope code S6.5.2), 8–11 m, U. Zajonz & F. N. Saeed, 6 April 2000 (ST- 718); SMF 29229, 1: Socotra Archipelago, Semha Island, NW coast, south of headland, biotope code 6.5.3, 18– 39 m, U. Zajonz & M. Apel, 7 April 2000 (ST-721).

Figures

FIGURE 10. Pseudochromis socotraensis, SMF 29200, 62.7 mm SL, holotype, east of Badh Issa, N coast of Abd al-Kuri Island, Socotra Archipelago. (Photo by P. Hurst)

FIGURE 11. Pseudochromis socotraensis, freshly dead, SMF 33550, 34.5 mm SL, Di Hamri, Socotra Island, Socotra Archipelago. (Photo by H. Pulch)

FIGURE 12. Pseudochromis socotraensis, live, same specimen as Figure 11. (Photo by H. Pulch)

FIGURE 13. Plot of number of circumorbital pores (average of left and right sides) against standard length for Pseudochromis aldabraensis (open circles), P. dutoiti (open squares), P. socotraensis (closed squares) and P. s p r i n g e r i (closed circles). Holotype values are indicated by arrows.