Lotilia Klausewitz, 1960

Shibukawa, Koichi, Suzuki, Toshiyuki & Senou, Hiroshi, 2012, Review of the shrimp-associated goby genus Lotilia (Actinopterygii: Perciformes: Gobiidae), with description of a new species from the West Pacific, Zootaxa 3362, pp. 54-64 : 55-57

Lotilia Klausewitz, 1960

Japanese name: Odori-haze zoku

Lotilia Klausewitz, 1960: 158 . Type species: Lotilia graciliosa Klausewitz 1960 , by original designation and monotypy.

Included species. Lotilia comprises two allopatric species, L. graciliosa (known from the Red Sea and adjacent areas) and L. klausewitzi sp. nov. (known from the West Pacific).

Diagnosis. Lotilia is distinguished from the other gobiine genera in having the following combination of characters: VI-I, 9–10 dorsal-fin rays; I, 9 anal-fin rays; 47–52 longitudinal scales; no scales on head and predorsal midline; scales on body cycloid anteriorly, ctenoid posteriorly; 10+16=26 vertebrae; P-V 3/II II I I 0/9; body stubby, its depth at anal-fin origin 18.2–23.6 % of SL; mouth moderate in size, not extending posteriorly to a vertical through posterior margin of eye; gill opening relatively narrow, extending anteriorly to a vertical through midoperculum; gill membranes broadly attached to isthmus, interspace between posteriormost points of right and left sides of gill-membrane attachments to isthmus (= narrowest interspace between right and left sides of gill opening) broader than pupil; distinct transverse pattern of sensory-papillae rows on cheek ( Fig. 1 ), including five transverse rows, viz. rows 1–5; rows 3 and 4 divided at midway by longitudinal row b; row b continuous and long, extending from a vertical through anterior half of eye to posterior part of cheek; a pair of short longitudinal rows of sensory papillae just behind chin (= row f); pectoral fin with distinct black spotted pattern. The vivid bicolor pattern, viz. blackish brown body with a broad pale area on dorsum from tip of snout to mid-base of first dorsal fin, followed by 2–3 small white saddles ( Fig. 2–3 ), is highly characteristic, and a similar pattern is found only in a few other gobiines (see “Comparison” below). Fishes of Lotilia are small, bottom-oriented coral-reef gobies, symbiotically associated with alpheid shrimps of the genus Alpheus .

Description. Dorsal-fin rays VI-I, 9–10; anal-fin rays I, 9; pectoral-fin rays 14–17; pelvic-fin rays I, 5; segmented caudal-fin rays 9+8, including 7+6–7 branched rays; dorsal unsegmented caudal-fin rays 5–7; ventral unsegmented caudal-fin rays 5–6; longitudinal scales 48–53; transverse scales from anal-fin origin dorsoanteriorly to first dorsal-fin base 19–22; transverse scales from anal-fin origin dorsoposteriorly to second dorsal-fin base 16–19; transverse scales from second dorsal-fin origin ventroposteriorly to anal-fin base 16–18; predorsal scales 0; circumpeduncular scales 20–22; gill rakers 3–4+11–13=14–17; pseudobranchial filaments 5–8; vertebrae 10+16=26; P-V 3/II II I I 0/9; epural 1; anal-fin pterygiophores anterior to first haemal spine 2.

Body relatively short and deep (body depth at anal-fin origin 18.2–23.6 % of SL), compressed posteriorly. Head slightly compressed, width of head 78.6–92.8 % of its depth. Snout short, its length subequal or slightly longer than eye diameter (snout length 20.3–23.8 % of head length); snout does not protrude beyond upper lip; dorsal profile from tip of snout to nape gently curved (viz. not steeply descending before eye). Eye dorsolateral, moderately large, its diameter 19.4–22.5 % of head length; interorbital space moderately wide, its width narrower than pupil diameter and 8.1–12.1 % of head length. No cutaneous ridge along dorsal midline of nape. Gape oblique, forming an angle of about 30–50 degrees with body axis. Mouth terminal; jaws subequal; posterior end of jaws extending to posterior half of eye (but not extending beyond posterior margin of eye). Anterior nasal opening at tip of short tube; no fleshy flap at tip of anterior naris; posterior nasal opening a pore, closer to eye than to anterior naris. Tongue free from floor of mouth; anterior margin of tongue nearly truncate or very weakly emerginate. Posteroventral margin of lower lip interrupted at lower-jaw symphysis. Mental frenum undeveloped. Gill opening moderately wide, but not extending anteriorly to a vertical line through posterior margin of preopercle; gill membranes broadly attached to isthmus, width of posteriormost part of gill-membrane attachment to isthmus (= interspace between right and left sides of anteroventral edge of gill opening) broader than pupil. No fleshy projections on lateral wing of shoulder girdle. No bony projections along posterior margin of preopercle. Gill rakers on outer surface of ventral arm of first arch well developed, long and thin, finger- or blade-like; gill rakers on outer surface of dorsal arm of first arch distinctly shorter than dorsalmost raker on outer surface of ventral arm of first arch; ossified gill rakers developed on both outer and inner surface of all gill arches; first gill slit usually large, ventral ca.

one-seventh or one-eighth of ventral arm closed by membrane. Caudal peduncle moderately slender, its depth 52.0–64.1 % of caudal-peduncle length. First dorsal fin subequal to second dorsal fin in height; first dorsal fin close to second dorsal fin, but not connected by membrane; all dorsal-fin spines slender and flexible; all segmented rays of second dorsal fin branched. Origin of anal fin on a vertical line between bases of first and second segmented rays of second dorsal fin; height of anal fin slightly lower than second dorsal fin; anal-fin spine slender and flexible; all segmented anal-fin rays branched. Caudal fin oblong, symmetrical dorsoventrally; caudal-fin length 88.9–94.8 % of head length. Pectoral fin oblong, extending posteriorly beyond a vertical through anus; all pectoral-fin rays branched, excluding 1–2 lowermost and/or uppermost simple ray(s). Origin of pelvic fin slightly anterior to a vertical line through origin of first dorsal fin; pelvic fins united medially by well-developed frenum (between spines) and connecting membrane (between innermost rays); pelvic frenum moderately thin, with smooth posterior margin; all segmented pelvic-fin rays branched.

Body covered with cycloid scales anteriorly, ctenoid scales with peripheral cteni posteriorly; ctenoid-scale area wedge-shaped anterilrly, with the midside scales extending anteriorly to a vertical line through posterior end of first dorsal-fin base or anus; scales on pectoral-fin base, basal area of caudal fin, belly and prepelvic region cycloid; head, nape and narrow area on dorsum around first dorsal-fin base naked.

Teeth in both jaws conical, slender, more or less inwardly curved; upper jaw with 4–5 rows of teeth anteriorly, narrowing to 1–2 rows posteriorly; teeth on middle row(s) of upper jaw smaller than teeth in outermost and/or innermost rows; lower jaw with 3–4 rows of teeth anteriorly, narrowing to single row posteriorly; some posterior teeth on innermost row of lower jaw (located around midpoint of lower jaw) enlarged, sometimes canine-like; other teeth on lower jaw subequal in size; no teeth on vomer or palatine. Anterior part of vomer not projecting downward behind symphysis of upper jaw.

Cephalic sensory systems of two species of Lotilia are illustrated in Fig. 1 . Cephalic sensory canals present in Lotilia klausewitzi , whereas absent in L. graciliosa ; in L. klausewitzi , anterior oculoscapular canal with pores Bʹ, C (single), D (single), E, F, G and Hʹ and preopercular canal with pores Mʹ, N and Oʹ; right and left sides of anterior oculoscapular canals fused medially in interorbital space; posterior oculoscapular canal not developed. All cephalic sensory-papillae rows uniserial or comprising a single papilla, not forming multiple lines nor aggregations; distinct transverse pattern of sensory-papillae rows, comprising five transverse rows (rows 1–5), on cheek; rows 3 and 4 divided by longitudinal row b; row b continuous, long, extending anteriorly to a vertical line through anterior half of pupil; a pair of short longitudinal rows just behind chin (= row f); row n transverse, long; row s1 longitudinal. Sensory papillae on midlateral body form uniserial vertical rows, each row short and restricted, found on a single or, in some parts, two scales; three radiating rows of sensory papillae on caudal fin, each along the fourth, seventh and tenth branched caudal-fin rays; all three sensory papillae rows on caudal fin extend from posterior margin of scaled area to near distal end of each ray.

Comparison. Lotilia resembles the shrimp-associated goby genera Cryptocentrus , Myersina and Stonogobiops in having the following combination of features: five (5–7 in the other three genera) well-developed transverse sensory-papillae rows on cheek, two (2–3) rows of them divided at midway by long longitudinal row b; row f comprising a pair of short longitudinal rows of sensory papillae; the “Priolepis Group” (sensu Birdsong et al. 1988) pattern of axial skeletal features, viz. 10+16=26 vertebrae, P-V 3/II II I I 0/9, two anal-fin pterygiophores anterior to first haemal spine, and single epural; scales on body small, 48–53 (44 or more) in longitudinal series. Lotilia is readily distinguished from these three genera by having: narrow gill opening, not extending anteriorly to a vertical through posterior margin of preopercle (vs. gill opening broad, extending beyond a vertical through posterior margin of preopercle in the latter three genera); ossified gill rakers present on both inner and outer surface of all gill arches (vs. absent on inner and outer sides of first and second gill arches, respectively); and its characteristic vivid bicolor pattern of body (see also below). Mahidolia , another Indo-Pacific shrimp-goby genus, is also similar in sharing most of these features, but has slightly larger scales, viz. usually less than 40 in longitudinal scales ( Akihito et al. 2002); furthermore, Mahidolia differs from Lotilia in having: broader gill opening, extending anteriorly to well beyond a vertical through posterior margin of preopercle (vs. not extending anteriorly to a vertical through posterior margin of preopercle in Lotilia ); larger jaws, extending posteriorly to well beyond a vertical through posterior margin of eye at least in male (vs. not reaching posteriorly to a vertical through posterior margin of eye in both sexes); tall first dorsal fin, taller than second dorsal fin (vs. subequal to second dorsal fin in height); and dark oblique barred pattern on body (vs. barred pattern not found on body).

As well as several black spots on caudal and/or pectoral fins, its vivid bicolor pattern of head and body is highly characteristic for Lotilia . Similar bicolor pattern, viz. blackish body with broad pale area and/or small pale saddle-like blotches on dorsum of head and body, is found in some species of Cryptocentrus , including C. albidorsalis , C. nigrocellatus , C. leucostictus and C. maudae . However, these gobies are bottom dwellers, not showing hovering habits, and easily distinguished from Lotilia species by their different coloration of fins, more elongate body and steep snout.

Figures

FIGURE 1. Ventral (top), lateral (middle) and dorsal (bottom) views of heads of two species of Lotilia, showing cephalic sensory-canal pores (indicated by uppercase letters, except for AN and PN, which are defined below) and sensory papillae (indicated by lowercase letters). A) L. klausewitzi sp. nov., one of URM-P 3296, 21.5 mm SL, female; B) L. graciliosa, one of SMF 9581, 30.5 mm SL, male. AN and PN, anterior and posterior nares, respectively. Arrows show the position where the gill membrane is attached to isthmus. Drawn by K. Shibukawa.

FIGURE 2. Lateral (A and C) and dorsal (B and D) views of alcohol-preserved specimens of two species of Lotilia. A – B) L. klausewitzi sp. nov., paratype, one of URM-P 3296, 24.9 mm SL, female; C – D) L. graciliosa, one of SMF 9581, 30.5 mm SL, male.

FIGURE 3. Underwater photograph of Lotilia klausewitzi sp. nov., Iriomote-jima Island, Yaeyama Group of Ryukyu Islands, Japan (photographed by K. Yano).