Helcogramma
A genus of triplefin blennies with a continuous lateral line.
Helcogramma is a genus of triplefin blennies, part of the family Tripterygiidae. These fish live across the Indo-Pacific region and also in the South Atlantic Ocean near St Helena and Ascension islands.
Members of this genus share a continuous lateral line that curves downward toward the operculum, made up of 7 to 39 tubed scales. The first dorsal fin has three spines, the anal fin has one spine, and each pelvic fin has one spine and two rays. The head lacks scales, and there is usually a scaleless strip along the bases of the dorsal and anal fins. The joint between the caudal fin and the vertebrae contains five bones, called hypurals.
There are 41 recognized species in Helcogramma, including the whitespot triplefin, darktail triplefin, Ascension triplefin, hooded triplefin, black-throated triplefin, red-finned triplefin, Hudson's triplefin, hotlips triplefin, rosy triplefin, and many others.
- Family
- Tripterygiidae
- Distribution
- Indo-Pacific and South Atlantic Ocean off St Helena and Ascension
- Recognized species
- 41
- Lateral line pored scales
- 7–39
- First dorsal fin spines
- 3
- Anal fin spines
- 1
- Pelvic fin spines
- 1
- Pelvic fin rays
- 2
Lore & Background
The fishes in the genus Helcogramma are characterised by the possession of a continuous lateral line which bends down towards the operculum, comprising 7–39 tubular pored scales. There are three spines in the first dorsal fin and the anal fin has one spine; the pelvic fin has a single spine and two rays. The head is scaleless and normally the bases of the dorsal and anal fins have a scaleless strip. There are five bones in the joint between the caudal fin and the vertebrae, the hypurals.
Currently, 41 recognized species are listed in the genus, including Helcogramma albimacula (Whitespot triplefin), Helcogramma aquila (Darktail triplefin), Helcogramma ascensionis (Ascension triplefin), Helcogramma capidata (Hooded triplefin), Helcogramma decurrens (Black-throated triplefin), Helcogramma hudsoni (Hudson's triplefin), Helcogramma obtusirostris (Hotlips triplefin), and many others. The species are distributed across the Indo-Pacific and the South Atlantic, with some endemic to specific islands such as St Helena and Ascension.
Reader's Guide
The genus Helcogramma is notable within the triplefin family Tripterygiidae for its distinctive morphological features, particularly the continuous lateral line that bends toward the operculum and the specific fin spine counts. These characteristics help distinguish Helcogramma from other triplefin genera. The genus comprises 41 recognized species, many of which have common names reflecting their appearance or location, such as Whitespot triplefin, Darktail triplefin, and Ascension triplefin. The distribution of Helcogramma spans the Indo-Pacific and extends into the South Atlantic Ocean, including the remote islands of St Helena and Ascension, indicating a wide but patchy range. The species list includes names associated with researchers and locations, such as Helcogramma randalli (Randall's triplefin) and Helcogramma novaecaledoniae (New Caledonian triplefin), reflecting the taxonomic work done on this group. The genus serves as an example of the diversity within triplefin blennies and the ongoing discovery of new species, as shown by the inclusion of species described as recently as 2012.
Did You Know?
- Helcogramma has a continuous lateral line that bends down towards the operculum.
- The genus contains 41 recognized species.
- Helcogramma species are found in the Indo-Pacific and the South Atlantic off St Helena and Ascension.
- The pelvic fin in Helcogramma has a single spine and two rays.
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