This species was previously considered to represent a form of H. orthogoniata and may be seen identified as such both online and in published literature.
H. parclitella can be told apart from all congeners by the following unique combination of characters: dorsal surface of body always with 2 large, saddle-shaped markings, the first posterior to the head, the second covering the base of the dorsal-fin, with the two sometimes continuous on flank, only rarely a third blotch between dorsal and caudal fins; base of caudal-fin dark; 5 simple and 12-13 branched pectoral-fin rays; 75-77 lateral line scales.
H. confuzona, H. orthogoniata and H. parclitella appear very similar at first glance but can be told apart by a few characters, the most useful of which to aquarists are the dark markings extending from the snout over the dorsal surface. These form a series of variable saddle-shaped blotches in all three species but there are some marked differences.
For example in H. orthogoniata and H. parclitella the 'saddles' are noticeably broader, more regularly-shaped and well-defined than in H. confuzona and usually extend into the lower half of the body.
Further, H. parclitella always has two saddles and H. orthogoniata three, whereas in H. confuzona there may be up to four irregularly shaped markings which are often restricted to the upper half of the body. One shared feature is an additional dark bar at the caudal peduncle.
Another feature shared by members of the H. ocellata group is keeled scales; for example in H. bilineata each scale has a single, wide keel orientated posteriorly. In H. confuzona the keels are rounded and in H. ogilviei elongate; in both cases they're positioned at the posterior edge of the scale.
In H. orthogoniata, H. ocellata and H. parclitella a central, broad keel is flanked by two smaller ones. Other defining characters for H. parclitella include 5 branched anal-fin rays, 2 simple and 8-9 branched pelvic-fin rays, 5 simple and 12-13 branched pectoral-fin rays and 12-14 scale rows above the pelvic-fin origin.
The genus Homaloptera van Hasselt, 1823 has long been considered a polyphyletic assemblage (Kottelat, 1998)[3], and following Randall & Page (2015) the majority of members have been moved into other genera as recognized therein:
Homalopteroides Fowler, 1905 with 11 species (Homalopteroides wassinkii, H. modestus, H. rupicola, H. smithi, H. stephensoni, H. weberi, H. tweediei, H. indochinensis, H. nebulosus, H. yuwonoi, and H. avii), is the most diverse and widely distributed genus of species formerly in Homaloptera. It is known from northeast India, Myanmar, Thailand, Laos, Cambodia, Vietnam (? see Kottelat 2012:51), Peninsular Malaysia, Sumatra, Java, and Borneo.
Homalopterula Fowler, 1940 is only known to occur in Sumatra and consists of six species, five described from Aceh Province (H. heterolepis, H. ripleyi, H. modiglianii, H. amphisquamata, and H. vanderbilti) and H. gymnogaster from Sumatera Barat province.
Balitoropsis Smith, 1945 contains two species, B. zollingeri and B. ophiolepis. The original type species B. bartschi (Smith, 1945) is now considered synonymous with B. zollingeri.
Pseudohomaloptera Silas, 1953, which has not been valid since 1953, now contains six species (P. tatereganii, P. sexmaculata, P. leonardi, P. yunnanensis, P. vulgaris, and P. batek) and is known to occur in southern China, Thailand, Laos, Cambodia, Peninsular Malaysia, and Borneo.
Ghatsa Randall & Page, 2015, contains the type species G. montana Herre, 1945, and four tentatively assigned species (G. pillaii, G. menoni, G. santhamparaiensis, and G. silasi).
Homaloptera van Hasselt, 1823, consists of six species (H. ocellata [type species], H. bilineata, H. orthogoniata, H. ogilviei, H. confuzona, and H. parclitella) found in Myanmar, Thailand, Cambodia, Peninsular Malaysia, Sumatra, Java, and Borneo.
Homaloptera is distinguished by the following combination of characters: reddish tints on fins in life; dorsal-fin origin anterior to pelvic-fin origin; 7–8½, 8½ (M) branched dorsal-fin rays; 7 branched pelvic-fin rays; forked caudal fin; keeled scales; 20–27 predorsal scales; 59–73 total lateral-line scales; no adipose keel on caudal peduncle; anus closer to anal-fin origin than to pelvic-fin insertion; large rostral cap; 2 thick rostral barbels in close proximity to each other; thick triangular upper lip; fleshy pad between lateral portions of lower lip; absence of central furrow at isthmus.
All Homaloptera spp. make fascinating aquarium inhabitants and are often referred to as 'lizard' loaches due to their behaviour and appearance. Like all balitorids they have morphology specialised for life in fast-flowing water, i.e., the paired fins are orientated and extended horizontally, head and body flattened, belly depressed.
These features form a powerful sucking cup which allows the fish to cling tightly to solid surfaces. The ability to swim in open water is greatly reduced and they instead appear to crawl and hop their way over rocks and other surfaces.
The family Balitoridae as recognised by Kottelat (2012) is widely-distributed across much of the Indian subcontinent, Southeast Asia and China.
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