94 



PH. GREENWOOD 



The family Latridae 



There are clear-cut differences in certain aspects of the 

 ligamentous and other connective systems in the two latrid 

 species examined, namely the monotypic genus Mendosoma 

 lineatum (Gay) and the species Acantholatris monodactylus 

 (Carmichael) of that polytypic genus. Also, an upper division 

 of the adductor mandibulae muscle A x is absent in A. 

 monodactylus whereas in Mendosoma it is an elongate, rather 

 thin element which lies lateral to the major part of the muscle 

 and extends over the greater part of its length. The minor 

 division, unlike the major one, has no direct connection with 

 the ligamentum primordium and inserts on the maxilla, 

 together with the major division, via the maxillary tendon of 

 the A, muscle. 



In Mendosoma the adductor mandibulae Aw division is a 

 very thin muscle, largely tendinous and with a single posterior 

 extension of its tendinous aponeurosis. This runs slightly 

 below the upper point of the articulation of the lower jaw 

 with the quadrate, to which bone it is attached a short 

 distance from the anterior border (Fig. 2; tendon 3). In other 

 words, it is of the basic percomorph type sensu Gosline 

 (1986), except that in Mendosoma it has one prolongation 

 extending along the symplectic, another running ventrally to 

 attach to the medial aspect of the preoperculum, a third, 

 directed dorsally to insert on the quadrate, and a fourth 

 directed obliquely backwards to attach to the ventral aspect 

 of the interoperculum medially and anteriorly. 



In all essentials, the adductor mandibulae Aw tendon 

 system's extension onto the interoperculum and preopercu- 

 lum in Mendosoma is very similar to that in Acantholatris, 

 with that in Mendosoma, as it were, foreshadowing the more 

 clearly differentiated condition in Acantholatris (cf. Figs 2 & 

 3). 



There is no ligament-like connection between the mandible 

 and hyoid arch in Mendosoma (cf. Acantholatris; Fig. 3). 



The epihyal-interopercular ligament is stout and short, 

 connecting the lateral aspect of the epihyal with the dorsal 

 margin of the interoperculum a short distance anterior to its 

 slightly raised facet for articulation with the epihyal. Unlike 

 the backward-facing facet in those cirrhitids in which it 

 occurs, that in M. lineatum faces forward (Fig. 2), as it does in 

 the other latrid examined (Acantholatris monodactylus; and 

 in the cheilodactylids dissected). 



A discrete interhyal-interopercular ligament (present in 

 cirrhitids) is apparently lacking in M. lineatum (as it is also in 

 Acantholatris, and Cheilodactylus) . 



Like the two latter genera, but not in the cirrhitids exam- 

 ined, Mendosoma has a well-developed interhyal- 

 preopercular ligament and another, more dorsally placed 

 ligament between the interhyal and the metapterygoid (Fig. 



2; lig. 7). This latter ligament I consider to be the homologue 

 of the interhyal-quadrate ligament in Cheilodactylus, and the 

 ligament in Acantholatris which runs from the interhyal to 

 both the quadrate and the entopterygoid (see p. 98 & p. 99 

 respectively). 



Mendosoma has discrete lateral and medial divisions of the 

 mandibulo-interopercular ligament, with the medial division 

 terminating a short distance behind the anterior tip of the 

 interoperculum (Fig. 2; lig. 6), and the lateral division 

 extending much further posteriorly. 



The anguloarticular-dentary ligament is short and stout, 

 markedly stouter than in any cirrhitid species examined, and 

 stouter than that in Acantholatris. 



As compared with the ligamentous and other connective 

 tissue systems in Mendosoma lineatum, those in Acantholatris 

 monodactylus are considerably more complex, (as they are 

 when compared with the cirrhitid species studied). As was 

 noted earlier (p. 94), there is no obvious sub-division of the 

 adductor mandibulae A 1 muscle in A. monodactylus. How- 

 ever, anteriorly the upper third of the muscle, unlike the 

 other two-thirds, is free from the ligamentum primordium 

 and inserts on the maxilla only through the maxillary tendon, 

 to which the major part of the muscle is also attached. 



Acantholatris monodactylus has a substantial Aw portion of 

 the adductor mandibulae muscle. From the muscle's 

 mediolateral tendinous aponeurosis a stout and relatively 

 short branch (tendon 3 in Fig. 3) runs posteriorly to insert on 

 the anteromedial aspect of the preoperculum's horizontal 

 limb. 



A second stout and much longer tendon from the Aw 

 muscle (tendon 5 in Fig. 3) extends from the ventral margin 

 of the muscle above the anguloarticular bone, and runs 

 obliquely backwards to attach to the medial aspect of the 

 interoperculum a short distance from that bone's anterior tip. 

 This tendon, unlike tendon 3, is not derived from the 

 aponeurosis of the adductor mandibulae Aw muscle but 

 originates directly from the muscle itself. Immediately after 

 its origin, tendon 5 is attached to the anterodorsal aspect of 

 the anguloarticular's medial face. It then passes over that face 

 of the retroarticular, and attaches to the medial aspect of the 

 interoperculum a short distance from the bone's anterior tip. 

 Since this tendon links the mandible with the interoperculum 

 it would appear to be the functional equivalent of the 

 mandibulo-interopercular ligament in the other species 

 described above. However, a true and very long mandibulo- 

 interopercular ligament is also present in A. monodactylus 

 (Fig. 3; lig. 6). Anteriorly it has an extensive attachment to 

 the lateral face of the anguloarticular and retroarticular 

 bones, as well as another on the posterior face of the 

 retroarticular. From here the ligament extends across to, and 



Fig. 1 A: Cyprinocirrhites polyactic (Group I species) Medial aspect of the left lower jaw, cheek region and hyoid arch, viewed obliquely 

 from above, to show the mandibulohyoid connection (semi-schematic). The branchial skeleton is displaced to the right. About times natural 

 size. 1 : Mandibulohyoid connection; 2a: tendon from lower part of adductor mandibulae A, muscle to maxilla; 2b: continuation of tendon 

 2a, joining tendinous aponeurosis of adductor mandibulae muscle Aw. Lig. prim: Ligamentum primordium. 



B: Cirrhitops fasciatus (Group I species) Diagramatic representation of mandibulohyoid connection and related tendons; medial aspect of left 

 side to demonstrate the second form of tendinous relationships within species of Group I. Abbreviations as in Fig. 1 A. 



C: Paracirrhites forsteri (Group II species). Medial aspect of the right lower jaw, cheek region and hyoid arch, viewed somewhat dorsally; the 

 branchial skeleton and hyoid arch considerably displaced to the left and posteriorly in order to reveal the mandibulohyoid connection. 

 (Semi-schematic). About times natural size. 1: Posterior portion of mandibulohyoid connection, inserting partly on the quadrate, and partly 

 continuous with tendinous aponeurosis of the adductor mandibulae muscle Aw (Awt); 2b: ventral continuation of maxillary tendon of 

 adductor mandibulae muscle A,; 3: interopercular-mandibular ligament; 4: tendon of adductor mandibulae A 2 muscle; Lig. prim: 

 ligamentum primordium. 



