Mecistocephalus angusticeps

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Mecistocephalus angusticeps
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Myriapoda
Class: Chilopoda
Order: Geophilomorpha
Family: Mecistocephalidae
Genus: Mecistocephalus
Species:
M. angusticeps
Binomial name
Mecistocephalus angusticeps
(Ribaut, 1914)
Synonyms
  • Lamnonyx angusticepsRibaut, 1914

Mecistocephalus angusticeps is species of soil centipede in the family Mecistocephalidae. [1] This centipede is found in Kenya, Seychelles, and the Chagos Archipelago. [2] This species features only 47 pairs of legs rather than the 49 leg pairs usually observed in the genus Mecistocephalus . [3] [4]

Contents

Taxonomy and distribution

The French zoologist Henri Ribaut first described this species in 1914 based on a single adult female specimen found in 1911 in one of the Shimoni caves at sea level on the coast of Kenya. [5] [3] Ribaut originally described this species under the name Lamnonyx angusticeps. [5] In 1920, the American biologist Ralph V. Chamberlain moved this species to the genus Mecistocephalus. [6] Since then, this species has been found on several islands in the Indian Ocean. Finds have been recorded on islands in Seychelles (on Curieuse island, on Praslin island, and on Picard island and elsewhere on the Aldabra atoll) [3] [7] and on the Egmont Atoll in the Chagos Archipelago. [2]

Phylogeny

A phylogenetic analysis of 46 species in the family Mecistocephalidae based on morphology places M. angusticeps in a clade with two other Mecistocephalus species with only 47 pairs of legs, M. tahitiensis and an undescribed species found on the Marquesas islands in French Polynesia. This analysis places a clade with only 45 leg pairs in the most basal branch of a phylogenetic tree of the genus Mecistocephalus, with a sister group formed by species in this genus with 47 or more leg pairs, and the clade with only 47 leg pairs in the second most basal branch, with a sister group formed by species in this genus with 49 or more leg pairs. This analysis indicates that the common ancestor of the species in this genus had 45 leg pairs, and that species with more leg pairs evolved through a process that added segments and increased the number of legs incrementally, first to 47 pairs, then (for most species in the genus) to 49 pairs. [8]

Description

This species has only 47 pairs of legs and reaches 50 mm in length. The body is mostly yellow, with fine dark pigmentation on the dorsal surface, but the head and most anterior segments are a reddish brown. The head is longer than wide, with a length/width ratio of about 1.7 or 1.8, and the antennae are three times as long as the head is wide. The second maxillae are slender, each with a claw that tapers uniformly to a pointed tip. The first article of the forcipules features a small proximal tubercle and a similar small distal tubercle, the intermediate articles each feature a small tubercle, and the ultimate article features only a shallow emergence at the base. The sternum of the last leg-bearing segment has a trapezoidal shape and is more wide than long, with a notch on each lateral margin. [3] [9]

This species shares many features with other species in the genus Mecistocephalus. For example, like other species in this genus, M.angusticeps features a head with a transverse frontal line, a coxosternite of the first maxillae that is divided down the middle by a suture, and an undivided coxosternite of the second maxillae. [8] Furthermore, like other species in this genus, M. angusticeps features a head that is evidently longer than wide and second maxillae with claws. Unlike most other species in this genus, however, this species features only 47 leg pairs rather than the 49 pairs usually found in this genus. [3] [4]

Although both this species and its close relative M. tahitiensis have 47 leg pairs, other features distinguish these two species. For example, the lateral parts of the clypeus in M. tahitiensis feature groups of sensilla shaped like buttons, but these lateral groups are absent in M. angusticeps. Furthermore, the coxal projections of the first maxillae are elongate in M. angusticeps, at least twice as long as their maximum width, whereas in M. tahitiensis, these projections are longer than wide, but less than twice as long as their maximum width. Moreover, the mandible in the average adult of the species M. tahitiensis features only four or five fully developed pectinate lamellae, whereas the average number is larger in adults of the species M. angusticeps, falling in the range of eight to twelve fully developed pectinate lamellae. [8]

References

  1. ↑ Bonato, L.; Chagas Junior, A.; Edgecombe, G.D.; Lewis, J.G.E.; Minelli, A.; Pereira, L.A.; Shelley, R.M.; Stoev, P.; Zapparoli, M. (2016). "Mecistocephalus angusticeps (Ribaut,1914)". ChiloBase 2.0 – A World Catalogue of Centipedes (Chilopoda). Retrieved 2024-06-08.
  2. 1 2 Popovici, George; Edgecombe, Gregory D.; Hall, Daniel W. (2024). "New Chilopoda from the Chagos Archipelago". Journal of Natural History. 58 (41–44): 1885–1915 [1900]. Bibcode:2024JNatH..58.1885P. doi: 10.1080/00222933.2024.2395903 . ISSN   0022-2933.
  3. 1 2 3 4 5 Bonato, Lucio; Minelli, Alessandro (2010). "The geophilomorph centipedes of the Seychelles (Chilopoda: Geophilomorpha)". Phelsuma. 18: 9–38 [13–15].
  4. 1 2 Bonato, L.; Minelli, A. (2004). "The centipede genus Mecistocephalus Newport 1843 in the Indian Peninsula (Chilopoda Geophilomorpha Mecistocephalidae)" . Tropical Zoology. 17 (1): 15–63 [20, 56]. Bibcode:2004TrZoo..17...15B. doi:10.1080/03946975.2004.10531198. ISSN   0394-6975. S2CID   85304657.
  5. 1 2 Ribaut, H. (1914). "Myriapodes. I. Chilopoda". Voyage de Ch. Alluaud et R. Jeannel en Afrique Orientale (1911–1912). Résultats Scientifiques (in French). 16: 3–35 [23–25] – via Biodiversity Heritage Library.
  6. ↑ Chamberlin, Ralph V. (1920). "On chilopods of the family Mecistocephalidae". The Canadian Entomologist. 52 (8): 184–189 [185]. doi:10.4039/Ent52184-8. ISSN   1918-3240.
  7. ↑ Popovici, George; Edgecombe, Gregory D. (2025-02-21). "Centipedes (Myriapoda, Chilopoda) of Aldabra Atoll (Seychelles)". ZooKeys (1228): 225–273 [242–243]. Bibcode:2025ZooK.1228..225P. doi: 10.3897/zookeys.1228.143007 . ISSN   1313-2970. PMC   11871523 . PMID   40026388.
  8. 1 2 3 Bonato, Lucio; Foddai, Donatella; Minelli, Alessandro (2003). "Evolutionary trends and patterns in centipede segment number based on a cladistic analysis of Mecistocephalidae (Chilopoda: Geophilomorpha)" . Systematic Entomology. 28 (4): 539–579 [542–546, 549–551, 561, 563–564, 566–567, 577-578]. Bibcode:2003SysEn..28..539B. doi:10.1046/j.1365-3113.2003.00217.x. ISSN   0307-6970.
  9. ↑ Bonato, Lucio; Edgecombe, Gregory; Lewis, John; Minelli, Alessandro; Pereira, Luis; Shelley, Rowland; Zapparoli, Marzio (2010-11-18). "A common terminology for the external anatomy of centipedes (Chilopoda)". ZooKeys (69): 17–51. Bibcode:2010ZooK...69...17B. doi: 10.3897/zookeys.69.737 . ISSN   1313-2970. PMC   3088443 . PMID   21594038.
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