This should work, but I havent tested it out yet.
Make sure to plug in the body parts in body_default file. Tell me if you see it! next stop, TOTAL X-COM MOD!
[CREATURE:LOBSTERMAN]
[NAME:lobsterman:lobsterpeople:Lobsterman]
[SPECNAME:FEMALE:lobsterwoman:lobsterwomen:lobsterwoman]
[SPECNAME:MALE:lobsterman:lobstermen:lobsterman]
[TILE:'L'][COLOR:4:0:1]
[LARGE_ROAMING][LARGE_PREDATOR]
[BIOME:ANY_OCEAN]
[BIOME:LAKE_TROPICAL_SALTWATER]
[BIOME:LAKE_TEMPERATE_SALTWATER]
[BIOME:SWAMP_MANGROVE]
[BIOME:SWAMP_TEMPERATE_SALTWATER]
[BIOME:MARSH_TEMPERATE_SALTWATER]
[BIOME:SWAMP_TROPICAL_SALTWATER]
[BIOME:MARSH_TROPICAL_SALTWATER]
[FREQUENCY:100]
[AMPHIBIOUS][UNDERSWIM]
[NOPAIN][NOBONES][NOSKULL][CHITIN]
[BLOODTYPE:B]
[GENPOWER:5]
[POPULATION_NUMBER:20:30]
[CLUSTER_NUMBER:5:10]
[DAMBLOCK:5]
[MODVALUE:5]
[BUTCHERABLE_NONSTANDARD]
[CAN_LEARN][CAN_SPEAK]
[CANOPENDOORS]
[PREFSTRING:crushing claws]
[PREFSTRING:exoskeleton]
[PREFSTRING:multi-band scanning ability]
[BODY:HUMANOID_ARMLESS:UPPERBODY_PINCERS:LOWERBODY_PINCERS:2EYES:2LUNGS:HEART:GUTS:ORGANS:MOUTH:BRAIN:2ANTENNAE]
[MAXAGE:100:200]
[ATTACK:MAIN:BYTYPE:GRASP:grab:grabs:1:6:GORE][ATTACKFLAG_CANLATCH]
[CHILD:12][BABY:1][MULTIPLE_LITTER_RARE]
[SIZE:10]
[EQUIPS]
[FAT:1]
[ALL_ACTIVE]
[STANDARD_FLESH]
[SWIMS_INNATE][SWIM_SPEED:900]
[HOMEOTHERM:10040]
[BODY:LOWERBODY_PINCERS]
[BP:R_LB_PINCER:right lower pincer][CONTYPE:LOWERBODY][GRASP]
[BP:L_LB_PINCER:left lower pincer][CONTYPE:LOWERBODY][GRASP]
[BODY:2ANTENNAE]
[BP:RANTENNA:right antenna][CONTYPE:HEAD][SMALL]
[BP:LANTENNA:left antenna][CONTYPE:HEAD][SMALL]