Microbrotula geraldalleni, Schwarzhans, Werner & Nielsen, Jørgen G., 2012

Schwarzhans, Werner & Nielsen, Jørgen G., 2012, A new species of the Genus Microbrotula (Teleostei: Bythitidae) from Cenderawasih Bay, New Guinea, Indonesia, Zootaxa 3583, pp. 71-76 : 72-75

Microbrotula geraldalleni sp. nov.

( Table 1 , Figs. 1 , 2 )

Microbrotula species; Allen & Erdmann 2012: 137.

Material examined. (9 specimens, 33–41 mm SL). HOLOTYPE (41 mm SL, male)— MZB 21247, Indonesia, West Papua, Cenderawasih Bay, Pulau Nurage, 0302’S, 13450’E, 5–12 m, G.R. Allen and M.V. Erdmann, 10.11.2008, with rotenone. PARATYPES (33–40 mm SL, 2 males and 6 females)— MZB 21248, WAM P. 33046- 0 0 3 and ZMUC P771717, all same data as for holotype.

Diagnosis. Vertebrae 11+37–39=48–50, dorsal-fin rays 68-73, anal-fin rays 61-65, pectoral-fin rays 14, caudal-fin rays 6. D/ V 9-11; D/A 13–15; V/A 14–16. Head with continuous squamation across cheek, opercle and occiput except for triangular window above opercle. Abundant papillae on anterior half of head. Forward-curved spine at lower angle of preopercle, hidden by skin. Posterior mandibular pores 3, lower preopercular pores 2 to 3. No palatine teeth. Otolith moderately elongate, length to height 2.0–2.1; otolith length to colliculum length 2.6–3.0.

Description ( Figs. 1 , 2 ). The principle meristic and morphometric characters are shown in Table 1 . Head slender with pointed snout, slightly depressed above eyes. Head with continuous squamation on cheek, opercle and occiput, except for triangular scale-less window above opercle ( Fig. 2 ). Horizontal diameter of scales on body about 2 % SL. Maxillary ending far beyond eye, dorsal margin of maxillary covered by dermal lobe of upper lip, posterior end angular and vertically expanded. Small anterior nostril just above upper lip. Posterior nostril small, about one fifth the size of eye. Opercular spine thin, short, free. Weak forward-curved spine at lower angle of preopercle covered by skin. Anterior gill arch with 3 elongate rakers.

Head sensory pores ( Fig. 2 ). No supraorbital pores. Anterior infraorbital pores 3, no posterior infraorbital pores. Mandibular pores 6 (3 anterior and 3 posterior). Lower preopercular pores 2 or 3, no upper preopercular pore.

Dentition. Premaxillary with several, irregular rows of granular teeth and with a few fangs at symphysis. Teeth on vomer separated into two circular patches each with 4–6 fanglike teeth and with 4–8 minute teeth between the patches. Dentary with several irregular rows of granular teeth; males with longer, pointed teeth in inner row. Palatine edentate.

Otolith ( Fig. 2 ). Moderately elongate, length to height 2.0–2.1. Outline regular with slightly pointed anterior and posterior tips at same level. Ventral rim deepest anterior to its middle; dorsal rim shallow, smooth, without prominent angles. Otolith length to sulcus length 2.6–3.0. Sulcus positioned at centre of inner face, undivided, with single, oval colliculum. Ventral furrow distinct, far from ventral rim of otolith; dorsal depression moderate.

Axial skeleton. Neural spine of vertebrae 3–5 inclined and 6–8 depressed, with broad bases. Parapophyses present from vertebrae 6–7 to 10. Pleural ribs on vertebrae 2 to 10. First anal-fin pterygiophore not elongate.

Colour ( Fig. 1 ). Live colour orange on rear part of fish and vertical fins, darker orange shading into violet on trunk and head. Preserved specimens medium grey to brown.

Remarks. The above description and meristic characters differ in certain details and values from those given in Allen and Erdmann (2012). Allen and Erdmann's description did not reflect certain characters, which are difficult to investigate in these fishes, namely head pores and spine at the lower angle of the preopercle. The latter is usually covered by skin and requires some dissection. The meristics published in Allen and Erdmann were those originally provided by the senior author. However, caudal vertebrae and dorsal and anal fin rays are very difficult to recognize and count towards the tail. Later, the original x-rays were found to be of too poor quality for reliable counts. Therefore, new x-rays were made with several different exposure times allowing for a higher resolution of the critical areas and they revealed presence of dense and small rays and caudal vertebrae near the tail, which led to an increase of the original counts of the caudal vertebrae and the dorsal and anal fin rays.

Comparison. Microbrotula geraldalleni is readily recognized by its peculiar triangular scale-less window on the head above the opercle and the presence of 3 (rarely 2) lower preopercular pores. It belongs to the group of species with 6 caudal rays and 14 pectoral rays together with M. greenfieldi and M. punicea . The former is probably the most similar, with M. geraldalleni differing in the continuous head squamation (although with scaleless window) (vs. separated patches on cheeks, opercle and occiput), the presence of posterior mandibular and lower preopercular pores (vs. absent), higher dorsal and anal fin ray counts (68–73 and 61–65 vs. 62–70 and 58–61, respectively) and a D/V of 9–11 (vs. 7–8). Microbrotula bentleyi also shows a good overall resemblance to M. geraldalleni , with the latter differing in the continuous head squamation (vs. patchy), higher number of vertebrae (48–50 vs. 45–47), higher number of dorsal and anal fin rays (68–73 and 61–65 vs. 61–70 and 50–57), lower number of pectoral and anal fin rays (14 and 6 vs. [15] 16–17 and 7–8) and 3 (rarely 2) lower preopercular pores (vs. 1–2).

All nine specimens show a rather small variation of the head squamation and most morphometric and meristic characters (except for the number of vertebrae), confirming the value of the diagnostic characters.

Distribution. Apparently endemic to Cenderawasih Bay, Irian Jaya, New Guinea, Indonesia. Cenderawasih Bay is known to contain several endemic species, probably as a result of its partial isolation during its recent geological past ( Allen & Erdmann, 2012).

Etymology. The species is named in honour of Gerald Allen, Perth, for his outstanding contribution to the knowledge of fishes from the Indo West-Pacific and his many years of support of the senior author.

We wish to thank Gerald Allen (WAM) for providing the specimens described here, photographs of a freshly collected specimen and information to Cenderawasih Bay. We also thank Marcus Krag (ZMUC) for providing the photo of the preserved specimen.

Figures

FIGURE 1. Microbrotula geraldalleni n. sp. A, live figure of unspecified specimen of the type-series WAM P. 33046 - 011; B, Holotype, WAM P. 33046 - 003, male, 41 mm SL.

FIGURE 2. Microbrotula geraldalleni n. sp. A – B, Holotype, A, lateral view of head, B. dorsal view of head; C, Paratype, WAM P. 33046 - 011, female, 40 mm SL, lateral view of head; D, Holotype, median view of right otolith; E – F, Paratype WAM P. 33046 - 011, female, 39 mm SL, E, ventral view of right otolith, F, median view of right otolith.

Tables

TABLE 1. Meristic and morphometric characters of Microbrotula geraldalleni. Mean values are given in parentheses.

	Holotype	HT and 8 PT
Standard length in mm	41	33–-41
Meristic characters
Dorsal fin rays	73	68(70.4)73
Caudal fin rays	6	6
Anal fin rays	63	61(62.6)65
Pectoral fin rays	14	14
Precaudal vertebrae	11	11
Total vertebrae	48	48(48.8)50
Long gill rakers on anterior arch	3	3
D/V	10	9(10.1)11
D/A	13	13(13.9)15
V/A	14	14(14.9)16
Morphometric characters in % of standard length
Head length	32.0	31.5(31.9)32.5
Depth at origin of anal fin	18.5	18.2(18.8)19.5
Upper jaw length	16.5	15.5(15.8)16.5
Posterior maxillary height	6.1	5.3(6.1)6.6
Diameter of orbit	3.7	3.3(3.7)3.9
Interorbital width	5.4	4.2(4.8)5.4
Postorbital length	20.0	19.5(20.5)21.0
Prepelvic length	29.0	27.0(29.8)31.5
Preanal length	54	54(56.4)60
Predorsal length	47.0	46.0(47.5)49.5
Base of pelvic fins to anal fin origin	27.0	24.0(26.6)29.5
Pectoral fin length	18.5	15.5(17.4)19.5
Pelvic fin length	15.0	12.5(13.9)15.5
Acknowledgments